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Video: Using Sheep to Terminate Cover Crops in Organic Farming

mer, 2016/10/12 - 16:48

This video describes ongoing interdisciplinary research that explores how the use of domestic sheep—rather than traditional farming equipment—to manage fallow land and terminate cover crops may enable farmers who grow organic crops to save money, reduce tillage, manage weeds and pests, and reduce the risk of soil erosion. Researchers from Montana State University and North Dakota State University are working on a USDA-National Institute of Food and Agriculture (NIFA) Organic Transitions project: Reducing Tillage in Organic Crop Systems: Ecological and Economic Impacts of Targeted Sheep Grazing on Cover Crops and Weed management, Soil Health and Stability, Carbon Sequestration and Greenhouse Gas Emissions. Additional information about the project is available on the Montana State University website here.

Researchers: Fabian Menalled, Patrick Hatfield, Perry Miller, Anton Bekkerman, Devon Ragen
Camera: Steve Spence, Casey Kanode, Jared Berent
Editing: Case Kanode, Steve Spence

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

eOrganic 13042

Hairy Vetch for Cover Cropping in Organic Farming

jeu, 2016/09/22 - 16:36

Source:

Adapted from: Clark, A. (ed.) 2007. Managing cover crops profitably. 3rd ed. National SARE Outreach Handbook Series Book 9. National Agricultural Laboratory, Beltsville, MD. (Available online at: http://www.sare.org/publications/covercrops.htm) (verified 24 March 2010). Note: For this article, all information from the source that does not comply with organic certification regulations has been removed.

Vicia villosa

Type: winter annual or summer annual legume
Roles: N source, weed suppressor, topsoil conditioner, reduce erosion
Mix with: small grains, field peas, bell beans, crimson clover, buckwheat

Few legumes match hairy vetch for spring residue production or nitrogen contribution. Widely adapted and winter hardy through Hardiness Zone 4 and into Zone 3 (with snow cover), hairy vetch is a top N provider in temperate and subtropical regions. The cover grows slowly in fall, but root development continues over winter. Growth quickens in spring, when hairy vetch becomes a sprawling vine up to 12 feet long. Field height rarely exceeds 3 feet unless the vetch is supported by another crop. Its abundant, viney biomass can be a benefit and a challenge. The stand smothers spring weeds, however, and can help you replace all or most N fertilizer needs for late-planted crops.

Benefits Nitrogen source

Hairy vetch delivers heavy contributions of mineralized N (readily available to the following cash crop). It can provide sufficient N for many vegetable crops, partially replace N fertilizer for corn or cotton, and increase cash crop N efficiency for higher yield.

In some parts of California and the East in Zone 6, hairy vetch provides its maximum N by safe corn planting dates. In Zone 7 areas of the Southeast, the fit is not quite as good, but substantial N from vetch is often available before corn planting.

Corn planting date comparison trials with cover crops in Maryland show that planting as late as May 15 (the very end of the month-long local planting period) optimizes corn yield and profit from the system. Spring soil moisture was higher under the vetch or a vetch-rye mixture than under cereal rye or no cover crop. Killed vetch left on the surface conserved summer moisture for improved corn production (A. J. Clark, personal communication, 2007; Clark et al., 1995, 1997b, 2007a; Hanson et al., 1993; Lichtenberg et al., 1994).

Even without crediting its soil-improving benefits, hairy vetch increases N response and produces enough N to pay its way in many systems. Hairy vetch without fertilizer was the preferred option for “risk-averse” no-till corn farmers in Georgia, according to calculations comparing costs, production, and markets during the study. The economic risk comparison included crimson clover, wheat and winter fallow. Profit was higher, but less predictable, if 50 pounds of N were added to the vetch system (Ott and Hargrove, 1989).

Hairy vetch ahead of no-till corn was also the preferred option for risk averse farmers in a three-year Maryland study that also included fallow and winter wheat ahead of the corn. The vetch-corn system maintained its economic advantage when the cost of vetch was projected at maximum historic levels, fertilizer N price was decreased, and the herbicide cost to control future volunteer vetch was factored in (Hanson et al., 1993). In a related study on the Maryland Coastal Plain, hairy vetch proved to be the most profitable fall-planted, spring-desiccated legume ahead of no-till corn, compared with Austrian winter peas and crimson clover (Lichtenberg et al., 1994).

In Wisconsin’s shorter growing season, hairy vetch planted after oat harvest provided a gross margin of $153/A in an oat/legume/corn rotation (1995 data). Profit was similar to using 160 lb. N/A in continuous corn, but with savings on fertilizer and corn rootworm insecticide (Stute and Posner, 1995).

Hairy vetch provides yield improvements beyond those attributable to N alone. These may be due to mulching effects, soil structure improvements leading to better moisture retention and crop root development, and soil biological activity and/or enhanced insect populations just below and just above the soil surface.

Soil conditioner

Hairy vetch can improve root zone water recharge over winter by reducing runoff and allowing more water to penetrate the soil profile through macropores created by the crop residue (Folorunso et al., 1992). Adding grasses that take up a lot of water can reduce the amount of infiltration and reduce the risk of leaching in soils with excess nutrients. Hairy vetch, especially an oats/hairy vetch mix, decreased surface ponding and soil crusting in loam and sandy loam soils. Researchers attribute this to dual cover crop benefits: their ability to enhance the stability of soil aggregates (particles), and to decrease the likelihood that the aggregates will disintegrate in water (Folorunso et al., 1992).

Hairy vetch improves topsoil tilth, creating a loose and friable soil structure. Vetch doesn’t build up long-term soil organic matter due to its tendency to break down completely. Vetch is a succulent crop, with a relatively low carbon to nitrogen ratio. Its C:N ratio ranges from 8:1 to 15:1, expressed as parts of C for each part of N. Rye C:N ratios range from 25:1 to 55:1, showing why it persists much longer under similar conditions than does vetch. Residue with a C:N ratio of 25:1 or more tends to immobilize N.

Early weed suppression

The vigorous spring growth of fall-seeded hairy vetch out-competes weeds, filling in where germination may be a bit spotty. Residue from killed hairy vetch has a weak allelopathic effect, but it smothers early weeds mostly by shading the soil. Its effectiveness wanes as it decomposes, falling off significantly after about three or four weeks. For optimal weed control with a hairy vetch mulch, select crops that form a quick canopy to compensate for the thinning mulch or use high-residue cultivators made to handle it. Mixing rye and crimson clover with hairy vetch (seeding rates of 30, 10, and 20 lb./A, respectively) extends weed control to five or six weeks, about the same as an all-rye mulch. Even better, the mix provides a legume N boost, protects soil in fall and winter better than legumes, yet avoids the potential crop-suppressing effect of a pure rye mulch on some vegetables.

A polyculture of crimson clover, cereal rye and hairy vetch used as a green manure cover crop for sweet corn.
Figure 1. A polyculture of crimson clover, cereal rye and hairy vetch used as a green manure cover crop for sweet corn. Planting polycultures increases plant and insect diversity, increases the number of ecosystem services, and decreases risk of crop failure. This photograph was taken in at the University of Florida's Plant Science Research and Education Unit in Citra, FL in early March, one week before termination. Photo credit: Danielle Treadwell, University of Florida.

Good with grains

For greater control of winter annual weeds and longer-lasting residue, mix hairy vetch with winter cereal grains such as rye, wheat or oats. Growing grain in a mixture with a legume not only lowers the overall C:N ratio of the combined residue compared with that of the grain, it may actually lower the C:N ratio of the small grain residue as well. This internal change causes the grain residue to break down faster, while accumulating the same levels of N as it did in a monoculture (Ranells and Wagger, 1997).

Moisture-thrifty

Hairy vetch is more drought tolerant than other vetches. It needs a bit of moisture to establish in fall and to resume vegetative growth in spring, but relatively little over winter when above-ground growth is minimal.

Phosphorus scavenger

Hairy vetch showed higher plant phosphorus (P) concentrations than crimson clover, red clover, or a crimson/ryegrass mixture in a Texas trial. Soil under hairy vetch also had the lowest level of P remaining after growers applied high amounts of poultry litter prior to vegetable crops (Earhart, 1996).

Fits many systems

Hairy vetch is ideal ahead of early-summer planted or transplanted crops, providing N and an organic mulch. Some Zone 5 Midwestern farmers with access to low-cost seed plant vetch after winter grain harvest in midsummer to produce whatever N it can until it winter-kills or survives to regrow in spring.

Widely adapted

Its high N production, vigorous growth, tolerance of diverse soil conditions, low fertility need, and winter hardiness make hairy vetch the most widely used of winter annual legumes.

Management Establishment and Fieldwork

Hairy vetch can be no-tilled, drilled into a prepared seedbed, or broadcast. Dry conditions often reduce germination of hairy vetch. Drill seed at 15 to 20 lb./A, broadcast 25 to 30 lb./A. Select a higher rate if you are seeding in spring, late in the fall, or into a weedy or sloped field. Irrigation will help germination, particularly if broadcast seeded. Plant vetch 30 to 45 days before killing frost for winter annual management; in early spring for summer growth; or in July if you want to kill or incorporate it in fall or for a winter-killed mulch. Hairy vetch has a relatively high P and K requirement and, like all legumes, needs sufficient sulfur and prefers a pH between 6.0 and 7.0. However, it can survive through a broad pH range of 5.0 to 7.5 (Duke, 1981). In Minnesota, vetch can be interseeded into sunflower or corn at last cultivation. Sunflower should have at least four expanded leaves or yield will be reduced (Kandel et al., 1997, 2000). Farmers in the Northeast’s warmer areas plant vetch by mid-September to net 100 lb. available N/A by mid-May. Sown mid-August, an oats/hairy vetch mix can provide heavy residue (Harlow, 1994).

A mixture of rye (30%) and vetch (70%) was planted as a green manure for sweet corn. Cereal rye has a erect growing habit and serves as an excellent trellis for vining legumes like hairy vetch.
Figure 2. A mixture of rye (30%) and vetch (70%) was planted as a green manure for sweet corn. Cereal rye has a erect growing habit and serves as an excellent trellis for vining legumes like hairy vetch. Photo credit: Danielle Treadwell, University of Florida.

Rye/hairy vetch mixtures mingle and moderate the effects of each crop. The result is a “hybrid” cover crop that takes up and holds excess soil nitrate, fixes N, stops erosion, smothers weeds in spring and on into summer if not incorporated, contributes a moderate amount of N over a longer period than vetch alone, and offsets the N limiting effects of rye (Clark et al., 1994, 1997a, 1997b, 2007b; Sideman, 1991). Seed vetch/rye mixtures, at 15-25 lb. hairy vetch with 40-70 lb. rye/A (Clark et al., 1994; Sarrantonio, 1994). Overseeding (40 lb./A) at leaf-yellowing into soybeans can work if adequate rainfall and soil moisture are available prior to the onset of freezing weather. Overseeding into ripening corn (40 lb./A) or seeding at layby has not worked as consistently. Late overseeding into vegetables is possible, but remember that hairy vetch will not stand heavy traffic (Sarrantonio, 1994).

Killing

Your mode of killing hairy vetch and managing residue will depend on which of its benefits are most important to you. Incorporation of hairy vetch vegetation favors first-year N contribution, but takes significant energy and labor. Keeping vetch residue on the surface favors weed suppression, moisture retention, and insect habitat, but may reduce N contribution. However, even in no-till systems, hairy vetch consistently provides very large N input (replacing up to 100 lb. N/A). In spring, hairy vetch continues to add N through its seed set stage after blooming.

Biomass and N increase until maturity, giving either greater benefit or a dilemma, depending on your ability to deal with vines that become more sprawling and matted as they mature. Mulch-retaining options include strip-tilling or mechanical killing (rotary mowing, flailing, cutting, sub-soil shearing with an undercutter, or chopping/flattening with a roller/crimper).

No-till corn into killed vetch

The best time for planting no-till corn into hairy vetch varies with local rainfall patterns, soil type, desired N contribution, season length, and vetch maturity. In southern Illinois, hairy vetch no-tilled into fescue provided 40 to 180 lb. N/A per year over 15 years for one researcher/farmer. He  killed the vetch about two weeks before the area’s traditional mid-May corn planting date. The 14-day interval was critical to rid the field of prairie voles, present due to the field’s thick fescue thatch. He kills the vetch when it is in its pre-bloom or bloom stage, nearing its peak N-accumulation capacity. Further delay would risk loss of soil moisture in the dry period customary there in early June. When the no-tilled vetch was left to grow one season until seed set, it produced 6 tons of dry matter and contributed a potentially polluting 385 lb. N/A (Townsend, 1994). This high dose of N must be managed carefully during the next year to prevent leaching or surface runoff of nitrates.

A series of trials in Maryland showed a different mix of conditions. Corn planting in late-April is common there, but early killing of vetch to plant corn then had the surprising effect of decreasing soil moisture and corn yield, as well as predictably lowering N contribution. The earlier-planted corn had less moisture-conserving residue. Late April or early May kill dates, with corn no-tilled 10 days later, consistently resulted in higher corn yields than earlier kill dates (Clark et al., 1995, 1997a, 1997b, 2007a). With hairy vetch and a vetch/rye mixture, summer soil water conservation by the cover crop residue had a greater impact on corn yield than spring moisture depletion by the growing cover crop (Clark et al., 1997b, 2007a).

Results in the other trials, which also included a pure rye cover, demonstrated the management flexibility of a legume/grain mix. Early killed rye protects the soil as it conserves water and N, while vetch killed late can meet a large part of the N requirement for corn. The vetch/rye mixture can conserve N and soil moisture while fixing N for the subsequent crop. The vetch and vetch/rye mixture accumulated N at 130 to 180 lb./A. The mixture contained as much N or more than vetch alone (Clark et al., 2007a, 2007b). In an Ohio trial, corn no-tilled into hairy vetch at mid-bloom in May received better early season weed control from vetch mulch than corn seeded into vetch killed earlier. The late planting date decreased yield, however (Hoffman et al., 1993), requiring calculation to determine if lower costs for tillage, weed control, and N outweigh the yield loss. Once vetch reaches about 50% bloom, it is easily killed by any mechanical treatment. To mow-kill for mulch, rye grown with hairy vetch improves cutting by holding the vetch off the ground to allow more complete severing of stems from roots. Rye also increases the density of residue covering the vetch stubble to prevent regrowth. Much quicker and more energy-efficient than mowing is use of a modified Buffalo rolling stalk chopper, an implement designed to shatter standing corn stubble. The chopper’s rolling blades break over, crimp, and cut crop stems at ground level, and handle thick residue of hairy vetch at 8 to 10 mph (Groff).

No-till vegetable transplanting

Vetch that is suppressed or killed without disturbing the soil maintains moisture well for transplanted vegetables. No-till innovator Steve Groff of Lancaster County, PA, uses the rolling stalk chopper to create a killed organic mulch. His favorite mix is 25 lb. hairy vetch, 30 lb. rye, and 10 lb. crimson clover/A.

University of Florida roller crimper. Roller crimpers terminate the crop by crimping the stems, thus interrupting the flow of nutrients and water through the plant. This system allows the plant residue to remain on the soil surface.
Figure 3. University of Florida roller crimper.

No-till, delayed kill

Farmers and researchers are increasingly using a roller/crimper to kill hairy vetch and other cover crops (ATTRA Question of the week). Jeff Moyer and others at the Rodale Institute in Kutztown, PA, roll hairy vetch and other cover crops in late May or early June (at about 50% flower). The modified roller is front-mounted, and corn is no-tilled on the same pass (The no-till + page). Also useful in killing hairy vetch on raised beds for vegetables and cotton is the improved prototype of an undercutter that leaves severed residue virtually undisturbed on the surface (Creamer et al., 1995). The undercutter tool includes a flat roller attachment, which, by itself, usually provides only partial suppression unless used after flowering.

Vetch incorporation

As a rule, to gauge the optimum hairy vetch kill date, credit vetch with adding 2 to 3 pounds of N per acre per sunny day after full spring growth begins. Usually, N contribution will be maximized by early bloom (10-25 percent) stage. Cutting hairy vetch close to the ground at full bloom stage usually will kill it. However, waiting this long means it will have maximum top growth, and the tangled mass of mature vetch can overwhelm many smaller mowers or disks. Flail mowing before tillage helps, but that is a time- and horsepower-intensive process. Sickle-bar mowers should only be used when the vetch is well supported by a cereal companion crop and the material is dry (UC SAREP Cover Crop Resource Page).

flail chop vetch and rye
Figure 4. Flail chopper terminating hairy vetch and rye. Photo credit: Danielle Treadwell, University of Florida.

Management Cautions

About 10 to 20 percent of vetch seed is “hard” seed that lays ungerminated in the soil for one or more seasons. This can cause a weed problem, especially in winter grains. In wheat, a variety of herbicides are available, depending on crop growth stage. After a corn crop that can utilize the vetch-produced N, you can establish a hay or pasture crop for several years. Don’t plant hairy vetch with a winter grain if you want to harvest grain for feed or sale. Production is difficult because vetch vines will pull down all but the strongest stalks. Grain contamination also is likely if the vetch goes to seed before grain harvest. Vetch seed is about the same size as wheat and barley kernels, making it hard and expensive to separate during seed cleaning (Sarrantonio, 1994). Grain price can be markedly reduced by only a few vetch seeds per bushel. A severe freeze with temperatures less than 5°F may kill hairy vetch if there is no snow cover, reducing or eliminating the stand and most of its N value. If winterkill is possible in your area, planting vetch with a hardy grain such as rye ensures spring soil protection.

Pest Management

In legume comparison trials, hairy vetch usually hosts numerous small insects and soil organisms (House and Alzugaray, 1989). Many are beneficial to crop production (see below), but others are pests. Soybean cyst nematode (Heterodera glycines) and root-knot nematode (Meliodogyne spp.) sometimes increase under hairy vetch. If you suspect that a field has nematodes, carefully sample the soil after hairy vetch. If the pests reach an economic threshold, plant nematode-resistant crops and consider using another cover crop. Other pests include cutworms (Sarrantonio, 1994) and southern corn rootworm (Buntin et al., 1994), which can be problems in no-till corn; tarnished plant bug, noted in coastal Massachusetts (Bugg et al., 1990), which readily disperses to other crops; and two-spotted spider mites in Oregon pear orchards (Flexner et al., 1991). Leaving unmowed remnant strips can lessen movement of disruptive pests while still allowing you to kill most of the cover crop (Bugg et al., 1990).

Larva of Multicolored Asian Lady Beetle, Harmonia axyridis  Steven Jacobs
Figure 5. Larva of Multicolored Asian Lady Beetle, Harmonia axyridis. Photo credit: Steven B. Jacobs, Pennsylvania State University.

Prominent among beneficial predators associated with hairy vetch are lady beetles, seven-spotted ladybeetles (Bugg et al., 1990), and bigeyed bugs (Geocaris spp.). Vetch harbors pea aphids (Acyrthosiphon pisum) and blue alfalfa aphids (Acyrthosiphon kondoi) that do not attack pecans but provide a food source for aphid-eating insects that can disperse into pecans (Bugg, 1991). Similarly, hairy vetch blossoms harbor flower thrips (Frankliniella spp.), which in turn attract important thrip predators such as insidious flower bugs (Orius insidiosus) and minute pirate bugs (Orius tristicolor). Two insects may reduce hairy vetch seed yield in heavy infestations: the vetch weevil or vetch bruchid. Rotate crops to alleviate buildup of these pests (Sarrantonio, 1994).

Crop Systems

In no-till systems, killed hairy vetch creates a short-term but effective spring/summer mulch, especially for transplants. The mulch retains moisture, allowing plants to use mineralized nutrients better than unmulched fields. The management challenge is that the mulch also lowers soil temperature, which may delay early season growth (Sarrantonio, 1994). One option is to capitalize on high quality, low-cost tomatoes that capture the late-season market premiums.

How you kill hairy vetch influences its ability to suppress weeds

Durability and effectiveness as a lightblocking mulch are greatest where the stalks are left whole. Hairy vetch severed at the roots or sickle-bar mowed lasts longer and blocks more light than flailed vetch, preventing more weed seeds from germinating (Creamer et al., 1995; Teasdale and Mohler, 1993). Southern farmers can use an overwintering hairy vetch crop in continuous no-till cotton. Vetch mixed with rye has provided similar or even increased yields compared with systems that include conventional tillage, winter fallow weed cover and up to 60 pounds of N fertilizer per acre. Typically, the cover crops are no-till drilled after shredding cotton stalks in late October. Covers are spray killed in mid-April ahead of cotton planting in May. With the relatively late fall planting, hairy vetch delivers only part of its potential N in this system. It adds cost, but supplies erosion control and long-term soil improvement (Bloodworth and Johnson, 1995). Cotton yields following incorporated hairy vetch were perennial winners for 35 years at a northwestern Louisiana USDA site. Soil organic matter improvement and erosion control were additional benefits (Millhollon, 1994).

Note: An unmowed rye/hairy vetch mix sustained a population of aphid-eating predators that was six times that of the unmowed volunteer weeds and 87 times that of mown grass and weeds (Bugg et al., 1991).

Other Options

Spring sowing is possible, but less desirable than fall establishment because it yields significantly less biomass than overwintering stands. Hot weather causes plants to languish. Hairy vetch makes only fair grazing material; livestock do not relish it.

Harvesting seed

Plant hairy vetch with grains if you intend to harvest the vetch for seed. Use a moderate seeding rate of 10 to 20 lb./A to keep the stand from getting too rank. Vetch seed pods will grow above the twining vetch vines and use the grain as a trellis, allowing you to run the cutter bar higher to reduce plugging the combine. Direct combine at mid-bloom to minimize shattering, or swath up to a week later. Seed is viable for at least five years if properly stored (Sarrantonio, 1994). If you want to save dollars by growing your own seed, be aware that the mature pods shatter easily, increasing the risk of volunteer weeds. To keep vetch with its nurse crop, harvest vetch with a winter cereal and keep seed co-mingled for planting. Check the mix carefully for weed seeds.

Comparative Notes

Hairy vetch is better adapted to sandy soils than crimson clover (Ranells and Wagger, 1997), but is less heat-tolerant than 'Lana' woollypod vetch.

Cultivars

'Madison', developed in Nebraska, tolerates cold better than other varieties. Hairy vetches produced in Oregon and California tend to be heat tolerant. This has resulted in two apparent types, both usually sold as “common” or “variety not stated” (VNS). One has noticeably hairy, bluish-green foliage with bluish flowers and is more cold-tolerant. The other type has smoother, deep-green foliage and pink to violet flowers. A closely related species, 'Lana' woollypod vetch (Vicia dasycarpa), was developed in Oregon and is less cold tolerant than Vicia villosa. Trials in southeastern Pennsylvania with many accessions of hairy vetch showed big flower vetch (Vicia grandiflora cv. Woodford) was the only vetch species hardier than hairy vetch. 'Early Cover' hairy vetch is about 10 days earlier than regular common seed. 'Purple Bounty', released in 2006, is a few days earlier and provides more biomass and better ground cover than 'Early Cover'.

References and Citations
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  • Kandel, H. J., B. L. Johnson, and A. A. Schneiter. 2000. Hard red spring wheat response following the intercropping of legumes into sunflower. Crop Science 40: 731–736.
  • Lichtenberg, E., J. C. Hanson, A. M. Decker, and A. J. Clark. 1994. Profitability of legume cover crops in the mid-Atlantic region. Journal of Soil and Water Conservation 49: 582–585.
  • Millhollon, E. P. 1994. Winter cover crops improve cotton production and soil fertility in Northwest Louisiana. Louisiana Agriculture 37: 26–27.
  • The no-till + page [Online]. The New Farm, Rodale Institute, Kutztown, PA. Available at: www.newfarm.org/depts/notill/index.shtml (verified 4 April 2011).
  • Ott, S. L., and W. L. Hargrove. 1989. Profit and risks of using crimson clover and hairy vetch cover crops in no-till corn production. American Journal of Alternative Agriculture 4: 65–70.
  • Ranells, N. N., and M. G. Wagger. 1997. Grass-legume bicultures as winter annual cover crops. Agronomy Journal 89: 659–665.
  • Sarrantonio, M. 1994. Northeast cover crop handbook. Soil health series. Rodale Institute, Kutztown, PA.
  • Sideman, E. 1991. Hairy vetch for fall cover and nitrogen: A report on trials by MOFGA in Maine. Maine Organic Farmer & Gardener 18: 43–44.
  • Stute, J. K., and J. L. Posner. 1995. Legume cover crops as a nitrogen source for corn in an oat-corn rotation. Journal of Production Agriculture 8: 385–390.
  • Teasdale, J. R., and C. L. Mohler. 1993. Light transmittance, soil temperature and soil moisture under residue of hairy vetch and rye. Agronomy Journal 85: 673–680.
  • Townsend, W. 1994. No-tilling hairy vetch into crop stubble and CRP acres. SARE project report FNC93-028. North Central Region SARE, St. Paul, MN.
  • UC SAREP cover crop resource page [Online]. University of California Sustainable Agriculture Research & Education Program. Available at: http://www.sarep.ucdavis.edu/database/covercrops (verified 4 April 2011).

 

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

eOrganic 469

Biodesign Farm Disease Management Tables

mer, 2016/09/21 - 14:34

eOrganic authors:

Helen Atthowe, Biodesign Farm

Alex Stone, Oregon State University

This article is part of the Biodesign Farm Organic System Description

Table 1. Disease Management System Strategies and tools Implementation details I. System design   Optimize landscape and field design Fields were designed with aspect and airflow in mind.  Plant resistant/resilient germplasm When possible, varieties were selected for disease resistance. Design for spatial/temporal rotation The 3-year crop rotation was based on family (Solanaceae, Brassicaceae, Fabaceae) II. Soil building for disease suppression   Optimize quantity and quality of soil organic matter (SOM) Organic residues varied in carbon content and ease of decomposition. SOM increased from an average of 3.5 to 5.7% in Old field and from 3.3 to 5.2% in New Field. Reduce tillage Minimum tillage was practiced in the spring in Old field and only in crop rows in New field. Balance cations Biodesign's target was 65–70% Ca, 15–20% Mg, and 3–5% K. In Old field, ending ratios were: 70% Ca, 18.7% Mg, and 5.7% K. In New field, they were 77.1% Ca, 17.8% Mg, and 5.1% K. Match nitrogen supply with crop need Some organic residues had higher carbon:nitrogen ratio and thus supplied nitrogen slowly.  III. Cultural strategies   Irrigate to minimize foliar/fruit wetting Drip irrigation was managed to avoid foliar and fruit wetting in Old field. Both drip and sprinkler irrigation were used in New field. Manage groundcover The between-row living mulch was mowed selectively to maximize airflow and reduce disease risk.
Maximize airflow Mowed living mulch row middles; planted crops on raised beds; staked tomatoes and peppers.  Reduce rain/irrigation water splashing  Black plastic mulch on tomato, pepper, and eggplant crops to reduce splashing of pathogen spores with rain/irrigation water. IV. Supplemental inputs   Apply materials for disease management Disease pressure was never very great (likely due to a dry climate), so no pesticides were applied for disease management. In the early 1990s, compost tea (made with Biodesign's sheep and/or cattle manure compost) was applied to tomato foliage in the spring (one to three applications) in an effort to manage bacterial speck (Pseudomonas syringae pv. tomato). A Solo backpack sprayer was used to apply approximately 3 gal/300-foot row. This practice was abandoned by the late 1990s as it did not seem to be effective. V. Diagnosis, monitoring, recordkeeping, and decision making    Scout crops/monitor for diseases Scouting for diseases occurred weekly or twice per month. Keep records Harvest evaluations included disease incidence/severity. Use monitoring data to inform management decisions Bacterial speck (Pseudomonas syringae pv. tomato) was a problem in the 1990s, but monitoring records/history helped Biodesign modify the system to minimize disease risk. Table 2. Old Field Rotation: Crops and Amendments by Row 1994-2005¹  Row 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005   Cattle manure compost 12 tons/acre Cattle manure compost 10 tons/acre Cattle manure compost 7 tons/acre Cattle manure compost
5 tons/acre Sheep and cattle manure compost 5 tons/acre Sheep manure compost 2-4 tons/acre Sheep manure compost 2 tons/acre Sheep manure compost 2 tons/acre Sheep manure compost 2 tons/acre No compost No compost No compost   White clover LM

White clover + snail medic LM

White clover + snail medic LM White clover + snail medic LM White clover + snail medic LM White clover + parabinga medic LM Alsike clover LM Alsike clover + annual ryegrass LM Alsike clover + annual ryegrass LM Red clover LM Alsike clover LM Red clover + yellow sweet clover LM 1 Buckwheat Lettuce Tomato Broccoli Pepper Lettuce Tomato Broccoli Pepper Red clover Broccoli Pepper 2 Buckwheat Lettuce Tomato Broccoli Pepper Lettuce Tomato Broccoli Pepper Red clover Broccoli Pepper 3 Buckwheat Lettuce Tomato Broccoli Pepper Lettuce Tomato Broccoli Pepper Red clover Broccoli Pepper 4 Buckwheat Lettuce Tomato Bean/
Cucumber Pepper Lettuce Tomato Broccoli Pepper Red clover Eggplant Red clover 5 Buckwheat Flowers Tomato Lettuce Pepper Flowers Tomato Broccoli Pepper Red clover Tomato Red clover 6 Buckwheat Flowers Tomato Lettuce Eggplant Flowers Tomato Pea/Bean Tomato Brussels sprouts Tomato Red clover 7 Buckwheat Flowers Eggplant Lettuce Tomato Broccoli Eggplant Lettuce Tomato Brussels sprouts Tomato Red clover 8 Buckwheat Flowers Pepper Lettuce Tomato Broccoli Pepper Lettuce Tomato Cabbage Pepper Red clover 9 Buckwheat Broccoli Pepper Flowers Tomato Broccoli Pepper Lettuce Tomato Broccoli Pepper Red clover 10 Buckwheat Broccoli Pepper Flowers Tomato Broccoli Pepper Flowers Tomato Broccoli Pepper Brussels sprouts 11 Tomato Broccoli Pepper Eggplant Tomato Broccoli Pepper Eggplant Tomato Red clover Squash Brussels sprouts 12 Tomato Broccoli Pepper Pepper Tomato Eggplant Pepper Tomato Broccoli Red clover Lettuce Tomato 13 Tomato Broccoli Broccoli Pepper Flowers Tomato Broccoli Tomato Broccoli Red clover Alsike clover Tomato 14 Tomato Eggplant Broccoli Pepper Flowers Tomato Broccoli Tomato Broccoli Red clover Alsike clover Tomato 15 Tomato Tomato Broccoli Pepper Broccoli Tomato Broccoli Tomato Broccoli Red clover Alsike clover Tomato 16 Tomato Tomato Broccoli Flowers Broccoli Tomato Broccoli Tomato Broccoli Red clover Alsike clover Broccoli 17 Tomato Tomato Broccoli Flowers Broccoli Tomato Broccoli Tomato Eggplant Squash Alsike clover Broccoli 18 Tomato Tomato Lettuce Tomato Broccoli Tomato Lettuce Pepper Pea/Bean Pepper Alsike clover Broccoli 19 White clover Tomato Lettuce Tomato Bean/ Potato Pepper Lettuce Pepper Carrot/ Lettuce Pepper Alsike clover Broccoli 20 White clover Tomato Lettuce Tomato Squash Pepper Lettuce Pepper Flowers Pepper Cabbage Eggplant 21 White clover Pepper Lettuce Tomato Lettuce Pepper Lettuce Pepper Alsike lover Pepper Brussels sprouts Mixed vegetables 22 White clover Pepper Flowers Tomato Lettuce Pepper Flowers Pepper Alsike clover Eggplant Brussels sprouts Yellow sweet clover 23 White clover Pepper Flowers Tomato Lettuce Pepper Flowers Alsike clover Alsike clover Tomato Alsike clover Yellow sweet clover 24 White clover Pepper White clover Tomato Lettuce White clover Alsike clover Alsike clover Alsike clover Tomato Alsike clover Yellow sweet clover 25 White clover Pepper White clover Buckwheat White clover White clover Alsike clover Alsike clover Alsike clover Tomato Alsike clover Yellow sweet clover

¹LM=Living Mulch

Table 3. New Field Rotation: Crops and Amendments by Row 1993-20010¹ Row 1993-2004 2005 2006 2007 2008 2009 2010   No amendments  No amendments Sheep manure compost (4 tons/acre); concentrated application in crop rows.  Sheep manure compost (2 tons/acre); concentrated application in crop rows. + gypsum in crop row (100 lb/4-ft x 600-ft row)    No compost.  Alfalfa meal in crop row (50 lb/4-ft x 600-ft row)        No compost.  Alfalfa meal in crop row (50 lb/4-ft x 600-ft row)  No compost.                  Alfalfa meal in crop row (50 lb/4-ft x 600-ft row)   No amendments Red clover LM Red clover LM Red clover LM  Red clover LM Red clover LM Red clover LM 1 Pasture Red clover Broccoli Pepper Greens Red clover/ Smooth brome Pepper 2 Pasture Red clover Broccoli Pepper Squash Red clover/ Smooth brome Pepper 3 Pasture Red clover Cabbage Pepper Cucumber Red clover/ Smooth brome Pepper 4 Pasture Red clover Brussels sprout Tomato Mixed brassicas Red clover/ Smooth brome Tomato 5 Pasture Red clover Brussels sprout Tomato Mixed brassicas Red clover/ Smooth brome Tomato 6 Pasture Red clover Tomato Squash Late greens Red clover/ Smooth brome Squash 7 Pasture Red clover Tomato Broccoli Bean Red clover/ Smooth brome Brussels sprout 8 Pasture Red clover Tomato Broccoli Carrot Red clover/ Smooth brome Brussels sprout 9 Pasture Red clover Pepper Cabbage Greens Red clover/ Smooth brome Broccoli 10 Pasture Red clover Pepper Onion/Mixed greens Bean Red clover/ Smooth brome Cabbage 11 Pasture Pasture Pepper Pasture Pasture Pasture Pasture 12 Pasture Pasture Pasture Pasture Pasture Pasture Pasture 13 Pasture Pasture Pasture Pasture Pasture Pasture Pasture 14 Pasture Pasture Pasture Pasture Pasture Pasture Pasture 15 Pasture Red clover Onion Brussels sprout Tomato Potato/Broccoli  Onion/Mixed greens 16 Pasture Red clover Mixed greens Brussels sprout Tomato Brussels sprout Squash 17 Pasture Red clover Squash Potato Tomato Brussels sprout Red clover/ Smooth brome 18 Pasture Red clover Red clover Red clover Pepper Broccoli Red clover/ Smooth brome 19 Pasture Red clover Red clover Red clover Pepper Mixed vegetables Red clover/ Smooth brome 20 Pasture Red clover Red clover Red clover Broccoli Pepper Red clover/ Smooth brome 21 Pasture Red clover Red clover Red clover Cabbage Pepper Red clover/ Smooth brome 22 Pasture Red clover Red clover Red clover Broccoli Pepper Red clover/ Smooth brome 23 Pasture Red clover Red clover Red clover Brussels sprout Tomato Red clover/ Smooth brome 24 Pasture Red clover Red clover Red clover Brussels sprout Tomato Red clover/ Smooth brome 25 Pasture Red clover Red clover Red clover Red clover Eggplant/Tomato Red clover/ Smooth brome

¹LM=Living Mulch

Table 4. Disease Specific Strategies Disease Disease Trends¹ Practices² Pesticides Tomato bacterial speck (Pseudomonas syringae pv. tomato)

Crop: tomato DOWN

Practice 3-year crop rotation by crop family (Solanaceae, Brassicaceae, Fabaceae).                     

Raised beds and staked tomatoes/peppers to maximize airflow and black plastic mulch under tomatoes/peppers to decrease rain/irrigation splashing of spores onto fruit and foliage.

None
Compost tea made with Biodesign's sheep and/or cattle manure compost was applied to foliage in the early 1990s. This practice was abandoned in the late 1990s as it did not seem effective. Cucumber mosaic virus   (Bromoviridae:Cucumovirus)  

Crop: pepper DOWN

Mow the between-row living mulch to maximize airflow and reduce leaf wetness.

Add higher carbon/lower nitrogen soil amendments  to build high-organic-matter soils with a diverse and healthy soil microbial community.

Use drip irrigation and management to avoid foliar and fruit wetting.

Manage system to suppress aphids (as they are the vector for CMV).

None

¹Supporting data is from farmer communication and crop monitoring records.
²See Table 1.

This article is part of the Biodesign Farm Organic Systems Description.

Table of Contents:

 

 

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

eOrganic 15658

Biodesign Farm Insect Management Figures

mer, 2016/09/21 - 14:33

eOrganic authors:

Helen Atthowe, Biodesign Farm

Alex Stone, Oregon State University

This article is part of the Biodesign Farm Organic System Description

 

Figure 1. Total pounds/acre of organic insecticides applied to brassica, pepper, and tomato crops, 1993–2010. Bt-K (Bacillus thuringiensis var kurstaki) was applied to brassicas for cabbageworms, 1994–1998. M-pede (soap) was applied to peppers for aphids, 1995–2000. Bt-SD (Bacillus thuringiensis var San Diego) was applied to eggplant for Colorado potato beetle, 1995 and 1997. All sprays were applied with a 3 gallon Solo backpack sprayer. No sprays were applied on any Biodesign crops from 2001 through 2010, yet crop damage was low and yields were good, according to farm pest damage, yield records, and on-farm research in 1995/1996 and 2006.
(1) Bt-K = DiPel dust Bt (Bacillus thuringiensis var kurstaki) applied at 2 tsp/gal of water
(2) M-Pede insecticidal soap concentrate applied at 4–6 Tbl (2.5 fl oz)/gal of water 
(3) Bt-SD = Planet Natural Bt (Bacillus thuringiensis var San Diego), applied in 1995 and 1997 at 4–5 Tbl (2–2.5 fl oz)/gal of water. This product is no longer available.

 

Figure 2. Pepper yield and aphid/aphid parasite incidence on peppers 1996, 2006, and 2007. Yield and aphid (Myzus persicae) population densities were monitored in June 1996, 2006 and 2007 as part of on-farm experiments. Aphid parasites (Aphidius and Aphelinus species) were also monitored in 2006 and 2007. Aphid densities on 100 leaves from 10 sample plants were relatively consistent in June 1996 (272), 2006 (202), and 2007 (238). The percent parasitized aphids was 73 and 80% in 2006 and 2007, respectively. Lady beetle adults and larvae (Coleoptera: Coccinellidae), syrphid fly larvae (Diptera: Syrphidae), and aphid midge larvae (Aphidoletes aphidimyza) were also found on sample pepper leaves in 2006 and 2007, but in much lower numbers than parasitized aphids.


 

Figure 3. Average weekly predator/parasite incidence in living mulch row middles, 2006. On-farm research was conducted May–October 2006 in two 600-ft brussels sprouts rows and the living mulch row middles between crop rows. Weekly sweep net samples were collected for 11 weeks using a Gemplers® R13101 15” sweep net. Twenty pendular sweeps were completed through the red clover row middles and ten strokes in brussels sprouts rows in each of four randomized plots in no-spray treatments (4 samples per date). In this experiment, no-spray plots were designed to retain pest species, as well as arthropod predators and parasites, thus representing the natural pest-control capacity of Biodesign's system.

(1) Lady beetle adult and (2) Lady beetle larva (Coleoptera:Coccinellidae) population densities varied seasonally, but were highest earlier in the season (June and July). Adults were also observed in sweeps, but in lower densities than larvae.
(3) Nabid bug (Nabidae) population densities varied seasonally, but were highest later in the season, peaking in September.
(4) Minute pirate bugs (Anthocoridae) were abundant later in the season and were a major component of the living mulch predator community in August and September.
(5) Spiders (Araneae) and (6) Harvestmen (Opiliones) were a regular component of the living mulch predator community year-round.
(7) Wasp (various, including wasps in the Aphidiidae, Braconidae, and Aphelinidae families) population densities varied seasonally.
(8) Syrphid fly larvae (Diptera:Syrphidae) population densities varied seasonally.
Assassin bugs (Reduviidae), Syrphid fly adults (Diptera:Syrphidae), and lacewing adults and larvae (Chrysopidae) were also observed in sweeps, but in comparatively low density.

 

Figure 4. Average number of carabid beetles and spiders captured in pitfall traps on four sampling dates, 2006. On-farm research was conducted July–September 2006 to measure the incidence of ground-dwelling predators in Biodesign Farm's no-spray pest management system. One pitfall trap was placed in each of four randomized plots for one week on each of the four dates. (1) Carabid beetles (Carabidae) were observed in relatively high numbers throughout the crop growing season. (2) Spiders (Araneae) were a regular component of the living mulch predator community year-round.


Figure 5. Imported cabbageworm (ICW, Pieris rapae) adults (July 2004–2008) and larvae (at harvest, 1996 and 2004–2008) in broccoli. Adult ICW butterflies were monitored using sweep nets as part of an annual July butterfly count, 2004–2008. Population densities fluctuated from year to year, probably based on climate conditions. ICW larva population densities were monitored at harvest as part of on-farm experiments and during harvest field monitoring; average number per plant was low (< 0.08 / plant) 2004-2008. One hundred plants were sampled during harvest evaluations/field monitoring.

(1) ICW adults = Imported cabbageworm (Pieris rapae) moths
(2) ICW larvae = Imported cabbageworm (Pieris rapae) larvae

  

Figure 6. Brussels sprout yield and quality evaluation, 2006. On-farm research was conducted to study Biodesign Farm's natural enemy-based pest management system. Average pounds per plant of salable and unsalable sprouts were compared among three pest management treatments for imported cabbageworm (ICW, Pieris rapae): no-spray control (I), Bt-sprayed threshold (II), and pyrethrin/rotenone bimonthly sprays (III) . Treatments followed by different letters indicate significant differences (p<0.05).

Treatments:
(I) No-spray control: No treatment for ICW control. This treatment was designed to retain the pest species, as well as arthropod predators and parasites, and thus to be a measure of the natural pest-control capacity of Biodesign's natural enemy-based pest management system.
(II) Bt-sprayed threshold: selective sprays based on ICW population threshold: Eight applications of the insect-selective insecticides, Dipel dust Bt (Bacillus thuringiensis var. kurstaki) and Concern insecticidal soap, when pest density reached action thresholds based on the percentage of plants with one or more larvae. This threshold was adapted from the University of Minnesota Extension Service guidelines for cabbageworms (Pieris rapae) in cabbage (Hines, R. L., and W. D. Hutchison. 2001. Evaluation of action thresholds and spinosad for lepidopteran pest management in Minnesota cabbage. Journal of Economic Entomology 94: 190–196).
(III) Pyrethrin/rotenone bimonthly sprays: nonselective bimonthly sprays: Ten applications sprayed twice/month of the insect-non-selective insecticide Bonide liquid pyrethrin/rotenone (0.8% pyrethrin and 1.1% rotenone) at a rate of 2.6 ml/L of water, as labeled for control of ICW. Treatments were applied in the morning using a Solo 473P3 backpack-pump sprayer. Spraying began with the first appearance of ICW adults on 31 May and continued on a biweekly basis until 4 October.

This article is part of the Biodesign Farm Organic Systems Description.

Table of Contents:


 

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

eOrganic 16102

Biodesign Farm Insect Management Tables

mer, 2016/09/21 - 14:32

eOrganic authors:

Helen Atthowe, Biodesign Farm

Alex Stone, Oregon State University

This article is part of the Biodesign Farm Organic System Description

Table 1. Insect Pest Management System Strategies and tools1 Implementation details I. Landscape-level design   Design fields to favor biological control agents Small crop fields were bordered on four sides by native grassland/pasture: pasture (75%), native grassland/dryland shrub-steppe community (15%), and riparian areas (10%) (Overview Fig. 2).
Practice temporal rotation The 3-year rotation of crops was based on crop family (Solanaceae, Brassicaceae, Fabaceae). Design for spatial diversity Fields were bordered by native grassland and pasture habitat. Within fields, crops were diversified (some were allowed to mature and flower). Row middles consisted of clover/weed living mulches, which were allowed to flower. II. Soil building for insect pest suppression   Add organic soil amendments Organic residues were applied regularly (mostly surface applied, with some incorporation of residues in the spring). Materials included mowed living mulch residue and on-farm-made compost. Reduced tillage Minimum tillage was practiced in the spring. In New field, tillage was done only in crop rows. Optimize quantity and quality of soil organic matter (SOM) Organic residues varied in carbon content and ease of decomposition. SOM increased from an average of 3.5 to 5.7% in Old field and from 3.3 to 5.2% in New field. Increase below-ground plant diversity A living mulch was planted between crop rows. The living mulch contained diverse annual and perennial species with different rooting types. Optimize soil potassium levels Potassium was supplied by the organic residues. Potassium levels increased and were relatively high. Old field: Potassium increased from 145 ppm in 1993 to 713 ppm in 2003, and decreased to 323 ppm after Biodesign stopped manure compost application. New field: Potassium increased from 123 ppm in 1993 to 229 ppm in 2010. Match nitrogen supply with crop need Applied organic residues gradually supplied nitrogen due to some with higher carbon: nitrogen ratios. Optimize soil calcium levels and cation balance Ca increased from an average of 1,588 to 2,024 ppm and decreased from 77.9 to 68.7% in the Old field.New field: Increased from an average of 1,485 to 1,790 ppm and decreased from 78.8 to 77.1%. III. Habitat-building See also Selective Mowing Create diverse below-ground habitat A living mulch was planted between crop rows. The living mulch contained diverse annual and perennial species with different rooting types. Create diverse above-ground habitat at the landscape level Diverse habitat (native grassland, riparian areas, and pasture) was maintained on 95% of field margins. Most roads on the farm were covered with grass or perennial living mulch. Create diverse above-ground habitat at the field level The living mulch contained diverse annual and perennial species. Between 30 and 50% of total acreage was planted in cover crops. Crops were diverse, and some were allowed to mature and flower in crop fields. The three main crops were solanaceous (60%), brassicas (30%), alliums (5%), and other crops (5%). Use blooming winter and summer cover crops The living mulch bloom sequence extended from early April through late September. Some species were allowed to flower during the entire cropping season due to selective and reduced mowing. Provide winter cover and refuge for beneficial organisms The living mulch provided year-round habitat and/or cover. Install grassy beetle banks Rather than installing beetle banks, Helen maintained undisturbed grassy areas on field borders and undisturbed clover/weeds in the living mulch between crop rows. A 30-ft x 600-ft remnant pasture strip was left in the middle of the 6-acre New field (2005–2010) as a beetle refuge. Manage living mulch mowing to optimize predator/parasite populations Selective and reduced mowing of the living mulch all season, especially in the spring, enhanced ground-dwelling predator populations and provided pest control. IV. Monitoring and identification of insect pests/beneficials   Scout crops and monitor for pests and beneficials Scouting for insect and disease pests and beneficials was done every 5 to 20 days. Identify pests and beneficials Scouting for insect and disease pests and beneficials was done every 5 to 20 days. Keep records Spray records were kept, beginning in 1994. Pest incidence records were kept sporadically from 1994 to 2010. Use monitoring data to inform management decisions Sprays were applied only when pests reached a threshold, based on monitoring. On-farm thresholds were developed to include predator and parasite:pest ratios when natural enemy populations increased. V. Supplemental inputs   Use selective organic insecticides Bt and M-pede (soap) were used to avoid killing beneficial insects (Table 2). Reduce organic insecticide sprays Insecticide use decreased and/or was eliminated from the 1990s through 2010 (Fig. 1).

¹Strategy listed in the NRCS Soil Quality Initiative

 

 

 

Table 2. Pest-Specific Strategies, Biological Controls, Supplemental Pesticides and Outcomes Insect pest1 Pest trend2 System design/Management strategies Biological controls3 Off-farm inputs and supplemental pesticides Aphids: many spp., especially green peach aphid (Myzus persicae)vand potato aphid (Macrosiphum cuphurbiae)

Crops: pepper, eggplant, tomato, potato DOWN Landscape-level diversity, provided by small crop fields bordered on four sides by native grassland/pasture (Overview Fig. 2). *Syrphids, spiders, lady beetles, lacewings, earwigs, parasitoid wasps (Aphidius and Aphelinus species), aphid midge (Aphidoletes aphidomyza) 1995–2000: insecticidal soap (M-Pede) 2001–2010: no sprays Cabbage aphids (Brevicoryne brassicae)

Crops: brussels sprouts, broccoli DOWN Perennial and annual clover/weed living mulch in row middles to provide in-field/interspersed plant diversity, season-long pollen/nectar/seed food sources, and winter cover
*Syrphids, spiders, lady beetles, parasitoid wasps (Diaeretiella rapae)   Cabbageworms: imported cabbageworm (Pieris rapae), diamondback moth (Plutella xylostella), and cabbage looper (Trichoplusia ni)

Crops: broccoli, cabbage, brussels sprouts DOWN Reduced tillage
*Spiders, carabid beetles, lady beetles, lacewings, earwigs, nabid bugs, minute pirate bugs, birds 1994–1998:
Bt (Bacillus thuringiensis) 1998–2010: no sprays
Hooped row covers Brassica flea beetle (Phyllotreta cruciferae)

Crops: broccoli DOWN Diverse crops (allowed to flower) and a 3-year rotation of crops by crop family (Solanaceae, Brassicaceae, Fabaceae) **Carabid beetles, spiders Hooped row covers placed over transplanted brassicas in the spring for frost protection and to suppress flea beetles Solanaceous flea beetles: western potato flea beetle (Epitrix subcrinita) and potato flea beetle (Epitrix cucumeris)

Crops: eggplant, tomato DOWN Selective mowing of the annual and perennial living mulch to avoid disturbance of natural enemies at key pest pressure times **Carabid beetles, spiders Management of overhead sprinkler irrigation to discourage flea beetles Colorado potato beetle (Leptinotarsa decemlineata)

Crops: eggplant, tomato DOWN

Native shrub hedgerow (in New field only), planted 2005, matured 2006–2010

Perennial native plant insectary planting (New field only), planted 2005, matured 2006–2010

Perennial grass beetle bank (New field only), 2005–2010

 

*Predaceous stink bugs (Perillus bioculatus and Podisus maculiventris)
**lady beetles, carabid beetles, spiders 1995 and 1997: Bt (Bacillus thuringiensis San Diego) 1998–2010: no sprays

¹For a list of common pests and their management in Montana, see the High Plains Integrated Pest Management (HPIPM) Guide and the Pacific Northwest Insect Management Handbook.
²Supporting data is from spray records, farmer observations, crop monitoring records, and on-farm research.
³* = detected feeding on or parasitizing pests; ** = observed and hypothesized as control

This article is part of the Biodesign Farm Organic Systems Description.

Table of Contents:

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

eOrganic 15657

Biodesign Farm Soil Management System Figures

mer, 2016/09/21 - 14:32

eOrganic authors:

Helen Atthowe, Biodesign Farm

Alex Stone, Oregon State University

This article is part of the Biodesign Farm Organic System Description

 

Figure 1. Soil organic matter content (SOM) and cation exchange capacity (CEC): Old field 1993–2006. Soil organic matter (SOM) contents generally increased over time from 3.5 to 5.7% with application of compost and mowed living mulch residues. The rapid increase in SOM content in 1994 likely is due to tilling in a 50-year-old sod pasture and addition of 12 tons/acre of manure compost. Variation in the upward trend in 2001 and 2002 may be related to decreased rates of manure compost application (1999–2002). However, manure compost application was stopped after 2002, and SOM levels generally continued on an upward trend. Cation exchange capacity increased steadily over time from 10.2 to 16.8 meq/100g. All soil tests were taken in May from 0-10 inches with a 3/4-inch-diameter, 10-inch-long soil probe. Ten to 20 samples were taken, mixed in a bucket, and a two cup sample was sent for analysis. This was repeated for a total of 1-3 soil tests per sampling date. Samples were analyzed by A & L Western Agricultural Lab, Modesto, CA.

 

 

Figure 2. Soil organic matter (SOM) and cation exchange capacity (CEC), New field, 2005–2010. In 2005, SOM content was at 3.4% when New field was in permanent grass pasture; it generally increased over time to 5.2% in 2010. New field was cultivated for vegetable production with application of mowed and incorporated perennial living mulch residues (2006–2010) and low rates of compost (approximately 4 and 2 tons/acre, 2006–2007). Cation exchange capacity did not change over time. All soil tests were taken in May from 0-10 inches with a 3/4-inch-diameter, 10-inch-long soil probe. Ten to 20 samples were taken, mixed in a bucket, and a two cup sample was sent for analysis. This was repeated for a total of 1-6 soil tests per sampling date. Samples were analyzed by A & L Western Agricultural Lab, Modesto, CA.

 

 

Figure 3. Nitrate-nitrogen, potassium, and phosphorus trends, Old field, 1993–2006. Potassium increased from 145 ppm in 1993 to 713 ppm in 2003, during the time that Biodesign applied manure-based composts annually, and decreased to 323 ppm after Biodesign reduced and then ceased manure compost application. Nitrate-N trends also seem to be related to manure compost application rates; levels increased from lows of 15 ppm in 1993 to highs of 102 ppm in 1996 during and after the highest rates of manure compost application (7–12 tons/acre). Nitrate-N (N03) levels decreased to 33 ppm in 2006, after stopping manure compost application in 2003. Phosphorus levels (Bray P1) increased steadily from lows in 1993 of 9 ppm to highs in 2006 of 192 ppm. All soil tests were taken in May from 0-10 inches with a 3/4-inch-diameter, 10-inch-long soil probe. Ten to 20 samples were taken, mixed in a bucket, and a two cup sample was sent for analysis. This was repeated for a total of 1-3 soil tests per sampling date. Samples were analyzed by A & L Western Agricultural Lab, Modesto, CA.

 

 

Figure 4. Nitrate-nitrogen, potassium, and phosphorus trends, New field, 2005–2010. Vegetable production began in 2006 in New field. Nitrate-N (N03) increased from lows of 13 ppm in 1993 to highs of 71 ppm in 2008 and 47 in 2010. Potassium (K) increased from 149 ppm in 1993 to 229 ppm in 2010. Phosphorus (Bray P1) levels increased from lows in 1993 of 8 ppm to highs in 2010 of 55 ppm. With lower rates of manure compost application (approximately 2-4 tons/acre), levels of soil K, P, and NO3 never reached the high to excessive levels recorded in Old field, and there were no problems with increasing pH. There was a jump in N03 and P1 in 2005 (compared to 1993 soil tests) due to incorporation of grass/weed/clover pasture (Table 6). All soil tests were taken in May from 0-10 inches with a 3/4-inch-diameter, 10-inch-long soil probe. Ten to 20 samples were taken, mixed in a bucket, and a two cup sample was sent for analysis. This was repeated for a total of 1-6 soil tests per sampling date. Samples were analyzed by A & L Western Agricultural Lab, Modesto, CA.

 



Figure 5. Monthly nitrate-nitrogen in minimum-till brassica crop rows compared to no-till brassica crop rows, New field, 2006 and 2007. Three random samples were taken in each of two 600-ft minimum-till and no-till brassica crop rows every month during the growing season (May–September) in 2006 and 2007. August samples were not taken in 2007. Compost was added to both crop rows in late April at a rate of approximately 4 tons/acre in 2006, and 2 tons per acre in 2007; however, because compost application was concentrated in crop rows only (avoiding row middles), actual compost rates were higher in the crop row. Clover living mulch was also incorporated into minimum-till rows both years in April. Soil nitrate-nitrogen (N) decreased during the growing season in both 2006 and 2007 in both till and no-till rows. In minimum-till rows, N levels were high both years in May (82 and 66 ppm, respectively) 2- 3 weeks after living mulch and compost was incorporated into crop rows; levels dropped to 31.3 ppm (2006) and 28 ppm (2007) by September. In no-till brassica rows, N was generally lower than in minimum-till rows. Nitrogen dropped in September (both years) to 10 ppm (2006) and 20.3 ppm (2007). All soil tests were taken from 0-10 inches with a 3/4-inch-diameter, 10-inch-long soil probe. Ten samples were taken, mixed in a bucket, and a two cup sample was sent for analysis. This was repeated for a total of 3 soil tests per treatment per sampling date. Samples were analyzed by A & L Western Agricultural Lab, Modesto, CA.

 

 

Figure 6. Soil pH, 1993–2010. In Old field, soil pH increased from 6.9 in 1993 to 7.7 in 1999 during the period in which Biodesign was adding large quantities of manure-based compost. During this period, potassium reached excessive levels. Soil pH decreased only slightly to 7.6 (2004–2006) as manure applications and potassium levels decreased. In New field, where lower rates of manure compost were applied and potassium never reached excessive levels, soil pH remained relatively stable at about 6.8. All soil tests were taken in May from 0-10 inches with a 3/4-inch-diameter, 10-inch-long soil probe. Ten to 20 samples were taken, mixed in a bucket, and a two cup sample was sent for analysis. This was repeated for a total of 1-6 soil tests per sampling date. Samples were analyzed by A & L Western Agricultural Lab, Modesto, CA.

 

Figure 7. Soil calcium trends, Old field, 1993–2006. Percent calcium levels dropped after initial tillage in 1994 and then remained relatively stable. All soil tests were taken in May from 0-10 inches with a 3/4-inch-diameter, 10-inch-long soil probe. Ten to 20 samples were taken, mixed in a bucket, and a two cup sample was sent for analysis. This was repeated for a total of 1-3 soil tests per sampling date. Samples were analyzed by A & L Western Agricultural Lab, Modesto, CA.

 

 

Figure 8. Soil calcium trends, New field, 2005–2008. All soil tests were taken in May from 0-10 inches with a 3/4-inch-diameter, 10-inch-long soil probe. Ten to 20 samples were taken, mixed in a bucket, and a two cup sample was sent for analysis. This was repeated for a total of 1-6 soil tests per sampling date. Samples were analyzed by A & L Western Agricultural Lab, Modesto, CA.

 

Figure 9.Soil magnesium trends, Old field, 1993–2006. All soil tests were taken in May from 0-10 inches with a 3/4-inch-diameter, 10-inch-long soil probe. Ten to 20 samples were taken, mixed in a bucket, and a two cup sample was sent for analysis. This was repeated for a total of 1-3 soil tests per sampling date. Samples were analyzed by A & L Western Agricultural Lab, Modesto, CA.

 

 

Figure 10. Soil magnesium trends, New field, 2005–2008. All soil tests were taken in May from 0-10 inches with a 3/4-inch-diameter, 10-inch-long soil probe. Ten to 20 samples were taken, mixed in a bucket, and a two cup sample was sent for analysis. This was repeated for a total of 1-6 soil tests per sampling date. Samples were analyzed by A & L Western Agricultural Lab, Modesto, CA.

 

 

Figure 11. Mowed versus unmowed living mulch row middles, New field, 2006. Three random samples were taken in a 600-ft unmowed living mulch row middle between brussels sprouts and cabbage crop rows in June. After sampling, half of the row was mowed on 18 June 2006. Three random samples each were taken from mowed and unmowed treatments in July, August, and September. Nitrate-nitrogen was numerically lower in mowed plots in July, August and September. Due to the small sample size, only in August was there a statistically significant difference (significant difference indicated by asterisks; p = 0.001). Generally nitrate-nitrogen levels were lower in living mulch row middles than in crop rows because the perennial living mulch was not incorporated into the soil, continued to grow almost year-round, and Biodesign's goal in the New field was to concentrate compost application in crop rows only and avoid row middles. All soil tests were taken from 0-10 inches with a 3/4-inch-diameter, 10-inch-long soil probe. Ten samples were taken, mixed in a bucket, and a two cup sample was sent for analysis. This was repeated for a total of 3 soil tests per treatment and sampling date. Samples were analyzed by A & L Western Agricultural Lab, Modesto, CA.

 

 

Figure 12. Arbuscular mycorrhizae (AM) density under various tillage and weed management treatments, New field, 2007. Five random samples were taken from three replicates for each of five tillage treatments (no-till, minimum-till, tillage only, tillage + paper mulch, tillage + vinegar) in September during 2007 on-farm experiments. Soil samples were kept cool until analyzed by Dan Mummey, microbiologist at the University of Montana, Missoula. Extraradical hyphae lengths were measured as an indication of AM presence and density. Treatments with different letters are significantly different (p<0.05). The greatest AM density was observed in no-till plots; the second-greatest density occurred in minimum-till plots. The vinegar treatment resulted in the lowest AM density.

This article is part of the Biodesign Farm Organic Systems Description.

Table of Contents:

 




 





 

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

eOrganic 16080

Biodesign Farm Soil Management System Tables

mer, 2016/09/21 - 14:31

eOrganic authors:

Helen Atthowe, Biodesign Farm

Alex Stone, Oregon State University

This article is part of the Biodesign Farm Organic System Description

Table 1. Biodesign Soil Management System Strategies and tools Implementation details I. Soil organic matter building1 See also Living Mulch and Organic Residues. Optimize quantity of soil organic matter (SOM) Increased from an average of 3.5 to 5.7% in Old field and from 3.3 to 5.2% in New Field. Optimize quality of soil organic matter Diverse organic residues were added regularly throughout the growing season. Organic residues varied in carbon content and ease of decomposition. Maintain soil cover1 An annual or perennial legume/weed/grass living mulch was grown between vegetable crop rows. Use winter cover crops Winter cover was maintained by the year-round annual or perennial living mulch between crop rows. Total acreage in winter cover ranged from 50 to 75%. Use summer cover crops Summer cover was maintained by the year-round annual or perennial living mulch between crop rows. Total acreage in summer living mulch ranged from 30 to 50%.  Apply organic soil amendments and residues  Residues included mowed clover/weed living mulch, on-farm-made compost (stopped in later years), and alfalfa meal (later years only). Some materials were surface applied annually (mowed living mulch), and some were incorporated into crop rows in the spring (living mulch, compost, and alfalfa meal). Apply manure-based compost On-farm-made sheep or cattle manure compost was applied in Old field from 1993 through 2002 (Disease Table 2) and in 2006 and 2007 in New field (Disease Table 3).  No compost was applied from 2008 through 2010. Manure was obtained at no charge from neighboring ranches.  Apply plant-based compost No plant-based compost was available to purchase, and Biodesign did not have the materials to make a plant-based compost economically. On-farm clover and off-farm straw were added to the on-farm-made manure-based compost. Apply organic amendments with varying carbon:nitrogen ratios Organic residues with different C:N ratios (mowed living mulch residue and on-farm-made compost) were added spring, summer, and fall. Reduce tillage Minimum tillage was practiced in the spring (Old field) and only in crop rows (New field).  Diversify soil biota with crop and non-crop diversity1 The living mulch contained diverse annual and perennial species with different rooting types and depths, and different plant families (Table 4). Grow a living root in the soil year-round1 The annual and perennial living mulches maintained year-round presence of legume, weed, and grass roots.   Mow weeds to enhance nutrient cycling Weeds were a major component of the perennial and annual living mulch, which was mowed two to six times per year. Till weeds to enhance nutrient cycling Weeds were incorporated along with the living mulch each spring in Old field and in crop rows only in New field.  Apply organic nonliving mulches, such as straw None applied. Mowed residue from living mulch row middles was sometimes blown into crop rows with the mower. Maintain animals/livestock as part of the cropping system Sheep from a neighboring farm grazed on crop fields during the winter in some years until 2004.  II. Soil fertility building Table 2 shows Biodesign's soil health trends, targets, and amendments.

Nitrate-nitrogen, potassium, and phosphorus trends are shown in Fig. 3 (Old field) and Fig. 4 (New field).

See also Living Mulch and Organic Residues, Table 3, and Table 5. Match nitrogen supply to crop need Organic residues were applied gradually throughout the season to cycle/recycle nitrogen; some had higher C:N ratios. In some years, soil N levels were very high in the spring (May) when frozen soils thawed and organic residues were tilled into the soil; by the end of the growing season (September), they dropped. N may have been stored in perennial living mulch plant root/foliage biomass during the growing season and over the winter. N levels in clover living mulch foliage were tested and found to be relatively high in September. Optimize soil potassium levels K levels increased and were too high in the Old field until 2006 when they came down to a level within the target range. Old field levels were low, but came up to the target range. % K levels in clover living mulch foliage were tested and found to be relatively high in September. Optimize soil phosphorus levels P1 levels increased steadily to very high (excessive) levels in Old field and to target levels in New field. % P levels in clover living mulch foliage were tested and found to be relatively high in September. Optimize soil calcium levels Ca increased from an average of 1,588 to 2,024 ppm and decreased from 77.9 to 68.7% in the Old field.  New field: Increased from an average of 1,485 to 1,790 ppm and decreased from 78.8 to 77.1%.       

  Optimize soil magnesium levels Mg increased in the Old field from an average of 225 (1993) to 254 ppm (2006) . Percent of cation balance increased from 18.4 to 18.7%. New field: Increased from an average of 202 to 248 ppm.  Percent of cation balance decreased from 18 to 17.8%.

Optimize soil micronutrient levels Soil micronutrient levels were tested in 1994. All were in the moderate to high range, except boron (0.6 ppm) and copper (0.8 ppm), both of which were low. In 1996, micronutrients were tested in the white clover living mulch foliage; all levels were in the sufficient range. Optimize soil cation exchange capacity (CEC) Increased from  10.2 to 16.8 meq/100g in Old field and from 9.8 to 11.7 meq/100g in New field. Optimize soil cation balance Biodesign's target was 65–70% Ca, 15–20% Mg, and 3–5% K. In Old field, ending ratios were on target: 70% Ca, 18.7% Mg, and 5.7% K. In New field, they were 77.1% Ca, 17.8% Mg, and 5.1% K.
Optimize soil pH In Old field, soil pH increased from 6.9 in 1993 to high levels of 7.7 in 1999 then decreased slightly to 7.6 in 2004-2006. In New field, pH remained relatively stable at about 6.8. Apply off-farm soil amendments and fertilizers before planting Gypsum (22% Ca, 16% S) was applied in New field once in 2007, at a rate of 100 lb/4-ft x 600-ft row. When compost addition was stopped, alfalfa meal was added to crop rows in New field from 2008 through 2010, at 50 lb/4-ft x 600-ft row.  Apply off-farm soil amendments and fertilizers as a crop side-dress None applied. Apply foliar minerals and fertilizers None applied. Apply foliar compost teas Helen experimented with compost teas in the early 1990s, but stopped using them in the late 1990s. Rotate crops Crops were rotated by crop family (Solanaceae, Brassicaceae, Fabaceae) in a 3-year rotation. Use soil tests to measure soil trends Helen sampled soil for analysis every 1 or 2 years and did monthly soil tests during the growing season in 1995, 1996, 2006, and 2007 during on-farm experiments to test the effect of the living mulch and organic residue amendment system on nutrient cycling. Optimize irrigation to minimize evapotranspiration (ET) loss2 Biodesign used drip irrigation and sprinklers. Vegetables received 1 to 1.5 inches/week.

¹Strategy listed in the NRCS Soil Quality Initiative
²ET can be determined with the use of CIMIS data, in-field soil moisture measurement, or both.

Table 2. Soil Health Trends, Targets and Amendments Soil health indicator Trend Biodesign target Status/Trends (1993–2010) Amendments/Fertilizers
Soil organic matter (SOM) UP 3.5% minimum for Biodesign's sandy loam soils Increased from an average of 3.5 to 5.7% in Old field and from 3.3 to 5.2% in New field.  On-farm-made compost was applied  annually at 2 to 12 tons/acre (Disease Table 2 and Table 3). Compost application decreased and was stopped in later years (2003 in Old field, 2008 in New field).  Cation exchange capacity (CEC) UP 10–15 meq/100g Increased from  10.2 to 16.8 meq/100g in Old field and from 9.8 to 11.7 meq/100g in New field. Residues derived from the mowed living mulch were incorporated and surface applied applied annually (Table 3).  Nitrate-nitrogen (NO3) UP & DOWN 30–40 ppm during early years; 20–30 ppm in later years Old field: Increased from an average of 15 ppm (1993) to 102 ppm (1996), falling again to 33 ppm (2006). Nitrate-N levels were related to manure compost application rates. New Field: Increased from lows of 13 ppm (1993) to highs of 47 ppm (2010) in minimum-till crop rows.

Alfalfa meal was added to crop rows in New field only (2008–2010) at 50 lb/4-ft x 600-ft row.

Potassium (K) UP & DOWN 200–300 ppm;              3-5% of cation balance                               Old field: Increased sporadically from an average 145 ppm (1993) to 713 ppm (2003), falling again to 323 ppm (2006). Potassium levels were related to manure compost application rates. Cation balance ended at 5.7%. New field: increased from 123 ppm (1993) to 229 ppm (2010). Cation balance ended at 5.1%.

  Phosphorus (P)—P1
weak Bray UP 40–90 ppm  Old field: P1 levels increased steadily from 9 ppm (1993) to very high levels of 192 ppm (2006), even after manure compost applications were decreased in 1999 and stopped after 2002. New field: Increased from 8 ppm (1993) to 55 ppm (2010).
 

Supporting data is from regular soil tests taken from an average of multiple samples per year at the 0- to 12-inch depth. All samples were taken in May with a 3/4-inch-diameter, 10-inch-long soil probe and were analyzed by A & L Western Agricultural Lab, Modesto, CA.

Table 3. Living Mulch: White Clover Tissue Nutrient Content 1996¹ Month C:N ratio N (%) S (%) P (%) K (%) Mg (%) Ca (%) Fe (ppm) B (ppm) Zn (ppm) July 16 3.3 0.27 0.43 4.1 0.4 1.4 503 21 35 August 10 4.3 0.31 0.46 4.2 0.35 1.4 165 24 30 September 11 4.1 0.3 0.45 4.9 0.31 1.2 191 23 30 Sufficiency range2   4.26–5.50 0.21–0.40 0.26–0.5 1.71–2.50 0.26–1.00 0.36–2.00 51–350 21–55 21–50

¹Average of three samples each month in July, August, and September
²Bennett, W. F. 1993. Nutrient deficiencies and toxicities in crop plants. APS Press, St. Paul, MN.

Table 4. Weed Species in Pasture, Minimum and No-till Plots, and Containers: 2007 Weed species Weed life cycle1 Untilled pasture Minimum-till No-till Containers Amaranthus retroflexus A   X   X Stellaria media A   X   X Solanum nigrum  A   X   X Thlaspi arvense  A   X X X Chenopodium berlandieri A   X X X Lactuca serriola A   X   X Portulaca oleracea  A   X   X Sisymbrium altissimum  A       X Echinochloa crus-galli  A       X Malva neglecta B X X X X Hyoscyamus niger B       X Plantago lanceolata P X       Plantago major  P   X     Taraxacum officinale  P X X     Silene alba  P X X X   Achillea millefolium  P X       Chrysanthemum leucanthemum  P X       Ranunculus acris  P X       Total annuals   0 7 2 9 Total biennials   1 1 1 2 Total perennials   6 3 1 0

¹ A = annual
  B = biennial
  P = perennial

Table 5. Compost and Manure Nutrient Analyses Year   N (%) P2O5 (%) K2O (%) S (%) Mg (%) Ca (%) Na (%) Fe (ppm) Al (ppm) Mn (ppm) Cu (ppm) Zn (ppm) Moisture content (%) 1995 Manure 0.7 0.57 1.28 0.16 0.3 1.35 0.13 1,593 1,102 125 11 24 53.1 1995 Cattle Manure Compost¹ 0.65 0.43 0.57 0.12 0.25 1.16 0.03 1,073 747 99 6 22 60.2 2006 Sheep Manure Compost² 0.67 0.49 0.82 0.14 0.26 1.31 0.07 1,233 538 114 7 23 61.8

¹1995 Compost was made with cattle manure, straw, and clover
²2006 Compost was made with sheep manure, straw and clover

Table 6. Soil Nutrient Analyses: New Field No-till and Tilled Treatments 2005¹  Treatment2 Organic matter Nitrogen Phosphorus N:P Ratio Potassium Magnesium Calcium pH CEC No-till 3.8 33.3 16.0 1.2 171.7 249.0 1,775.7 6.8 11.6 Tilled 3.4 61.3 27.0 4.0 155.3 233.0 1,709.7 6.5 11.8

¹New field was 60-year-old grass/weed/clover pasture before tillage.
²Three samples per treatment were analyzed 2 weeks after tillage. Samples were taken 15 April 2005 from 0-10 inches with a 3/4-inch-diameter, 10-inch-long soil probe. Ten samples were taken, mixed in a bucket, and a two cup sample was sent for analysis. This was repeated for a total of 3 soil tests per each of the two treatments. Samples were analyzed by A & L Western Agricultural Lab, Modesto, CA. 

Table 7. Well Water Analysis: 2000 and 2010 Test/Method code Results (mg/L) Date analyzed Critical value Nitrate EPA 300.0 < 0.60 17 Jul 20001 10 mg/L  Nitrate EPA 300.0 < 0.50 4 Sep 20102 10 mg/L 

¹Test performed as part of USGS Water-Resources Investigations Report 99-4219, Hydrogeology and Aquifer Sensitivity of the Bitterroot Valley, Ravalli County, Montana.
²Test performed for home inspection during farm sale.

This article is part of the Biodesign Farm Organic Systems Description.

Table of Contents:


 

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

eOrganic 15634

Biodesign Farm Disease Management System

mer, 2016/09/21 - 14:29

eOrganic authors:

Helen Atthowe, Biodesign Farm

Alex Stone, Oregon State University

This article is part of the Biodesign Farm Organic System Description

Outcomes

Introduction

Biodesign Farm evolved management strategies that optimized soil organic matter and soil fertility while implementing good cultural practices to minimize the need for pesticides (Table 1). Practices included:

  • Organic soil amendments to improve soil and crop quality
  • Soil building to build high organic matter soils with diverse and healthy soil microbial communities
  • Maintenance and selective mowing of the between-row living mulch to build soil quality, maximize air flow, and provide habitat for aphid predators
  • Drip irrigation and irrigation management to maximize air flow and reduce foliar and fruit wetness
  • Three-year rotation of crops by crop family (Solanaceae, Brassicaceae, Fabaceae)
  • Cultural practices including raised beds and staking of tomatoes and peppers to maximize airflow and reduce leaf wetness and disease severity
  • Black plastic mulch on tomato, pepper, and eggplant crops to reduce splashing of pathogen spores by rain or irrigation water onto the stems/leaves/fruit, thus reducing disease severity

The semiarid climate of Biodesign Farm also contributed to low disease risk. Precipitation is only 13–16 inches and occurs mainly in winter, fall, and early spring.

Outcomes Disease Incidence and Crop Quality

According to Helen, yield and quality losses to disease declined over 17 years, especially those resulting from tomato bacterial speck. This observation is supported by crop quality monitoring records (1994–2010).

  • Severity of tomato bacterial speck (Pseudomonas syringae pv. tomato) decreased over time and this disease did not occur from 2006–2010 in New field and from 1999–2005 in Old field. The dry climate and less intensive production in later years likely were contributing factors, although Biodesign's irrigation, black plastic, living mulch, and other practices may also have contributed to disease suppression.
  • Cucumber mosaic virus (Bromoviridae:Cucumovirus) was observed at very low levels on peppers in the early 2000s in Old field, but did not seem to affect crop yield. It was not observed from 2006–2010 in New field.
Pesticide Use

No pesticides were used to manage diseases at Biodesign Farm.

Key Practices Rotation

Biodesign Farm's rotation developed around market opportunities and emphasized solanaceous crops. Table 2 and Table 3 show the rotation history. The main focus was a rotation of plant families and crop nutrient needs. The general 3-year rotation for each row was as follows:

  • Year 1: Solanaceous crops—tomatoes, peppers, eggplants
  • Year 2: Brassica crops—broccoli, cabbage, brussels sprouts
  • Year 3: Legume living mulch (Fabaceae) and/or other crops in the Cucurbitaceae, Allium, and lettuce families

Because the field was small, solanaceous crops often abutted and occasionally overlapped. The clover row middles rotated from year to year and also figured into the rotation, but not in a carefully planned manner.

Disease-Specific Practices

Biodesign also utilized practices targeted to specific crops and disease life cycles (Table 4):

  • Tomato bacterial speck: (Pseudomonas syringae pv. tomato) was a problem during long, cool, humid springs when tomatoes were covered with Reemay day and night to protect them from frost. As soon as nighttime temperatures rose, days got sunny and dry, and Reemay was removed, tomato plants seemed to grow out of the symptoms. Drip irrigation was used in the spring to avoid wetting foliage and developing fruit. Raised beds and staked tomatoes helped to maximize airflow and may have reduced disease severity. Black plastic mulch helped to reduce splashing of rain or irrigation water, which can carry spores of disease organisms up to the stems/leaves/fruit. Biodesign's soil building practices generated a soil with high microbial activity, which likely decomposed crop residues quickly. Disease residues are a primary source of bacterial speck inoculum, so the microbially active soil likely contributed to suppression of this disease.  Compost tea (made with Biodesign's on-farm-made sheep and/or cattle manure compost) was applied to tomato foliage in the spring (one to three applications) in the early 1990s, using a 3-gallon Solo backpack sprayer and an application rate of approximately 3 gal/300-ft row. This practice was abandoned by the late 1990s because it did not seem to have much effect and because disease problems had diminished over time.
  • Cucumber mosaic virus (CMV, Bromoviridae:Cucumovirus) was observed at low levels on peppers in the early 2000s but not thereafter. When possible, Biodesign grew CMV-resistant pepper varieties such as Revolution, Vanguard, and Socrates X3R. As CMV is transmitted by aphids, aphid parasitism (Insect Fig.2) likely contributed to CMV suppression. 
Soil building

Biodesign's soil-building system was designed to build high organic matter soils with a diverse and healthy soil microbial community. High-nitrogen (N) and lower carbon (C) soil amendments were applied in early years in Old field (1993–1996); higher C amendments were applied in later years. By 1999, manure-based compost rates had been reduced significantly, as mowed living mulch residues became more important (Table 2). In New field, Helen used higher C/lower N amendments from the start (Table 3).

Soil test records indicate a rise in soil organic matter (Soil Fig. 1) and, after 1996 in Old field, a decreasing trend in soil nitrate-N (Soil Fig. 3). Analysis of soil microbial population density in 1995 and 2007 showed relatively high levels of total microbial biomass and arbuscular mycorrhizal fungi. Some level of biological control may have been generated by the farm's soil amendments and soil-building practices, since damage from disease decreased over time.

Irrigation

In the beginning (Old field), drip irrigation was used almost exclusively to avoid wetting tomato foliage and minimize the environmental conditions that favor tomato bacterial speck. Some sprinkler irrigation was used to keep the living mulch row middles irrigated. By 2000, Biodesign was using both sprinkler and drip irrigation in Old field to irrigate all crops, including tomatoes. In New field (2005–2010), mostly sprinkler irrigation was used because the source was a gravity-flow, surface-water system (thereby eliminating energy costs). In New field, disease pressure was low, so disease avoidance was not the main priority when making irrigation decisions.

Analysis: Integrating Practice and Research

Disease may have been suppressed by Biodesign's design and soil/habitat-building practices, since in later years diseases occurred at relatively low levels. See the eOrganic video: Organic No-Till Living Mulch Disease: Weed Em and Reap.

Cucumber Mosaic Virus (Bromoviridae:Cucumovirus)

Biodesign's goal was to build high organic matter soils with a diverse and healthy soil microbial community. Analysis of microbial population density in Biodesign soils during on-farm experiments in 1996 and 2007 showed relatively high levels of total microbial biomass and arbuscular mycorrhizal fungi. There is some evidence to support Biodesign's hypothesis that microbes in healthy soil increase resistance to cucumber mosaic virus (Zehnder et al., 2000; Ryu et al., 2004; Elsharkawy et al., 2012). Aphid suppression may also have played a role. See Insect Management System.

References and Citations
  • Ryu C. M., J. F. Murphy, K. S. Mysore, and J. W. Kloepper. 2004. Plant growth-promoting rhizobacteria systemically protect Arabidopsis thaliana against Cucumber mosaic virus by a salicylic acid and NPR1-independent and jasmonic acid-dependent signaling pathway. The Plant Journal 39: 381–392. (Available online at: http://onlinelibrary.wiley.com/doi/10.1111/j.1365-313X.2004.02142.x/abstract) (verified 13 Sep 2016)
  • Elsharkawy M. M., M. Shimizu, H. Takahashi, and M. Hyakumachi. 2012. The plant growth-promoting fungus Fusarium equiseti and the arbuscular mycorrhizal fungus Glomus mosseae induce systemic resistance against Cucumber mosaic virus in cucumber plants. Plant and Soil. 361(1): 397–409. (Available online at: http://dx.doi.org/10.1007/s11104-012-1255-y) (verified 13 Sep 2016)
  • Zehnder G. W., C. Yao, J. F. Murphy, E. R. Sikora, and J. W. Kloepper. 2000. Induction of resistance in tomato against Cucumber mosaic cucumovirus by plant growth promoting rhizobacteria. BioControl. 45:127–137. (Available online at: http://www.bashanfoundation.org/kloepper/kloeppercucmvirus.pdf) (verified 13 Sep 2016)
Additional Resources

This article is part of the Biodesign Farm Organic Systems Description.

Table of Contents:


 

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

eOrganic 15632

Biodesign Farm Insect Management System

mer, 2016/09/21 - 14:28

eOrganic authors:

Helen Atthowe, Biodesign Farm

Alex Stone, Oregon State University

This article is part of the Biodesign Farm Organic System Description

Introduction

Biodesign Farm's goal was to build and manage habitat for biological control organisms (insect predators and parasites, birds, bats, soil and foliar microorganisms), thereby suppressing pests, minimizing the use of insecticides, and producing high-quality crops.

Biodesign's insect pest management system (Table 1) included the following:

  • Landscape-level diversity, provided by small crop fields bordered on four sides by native grassland/pasture: pasture (75%), native grassland/dryland shrub–steppe community (15%), and riparian areas (10%)
  • Reduced tillage using seasonal (1990s) and permanent (2000s) living mulch row middles, minimum primary tillage, and no tractor-based weed cultivation. According to the results of 2006 on-farm research, reduced tillage may have enhanced survival of ground-dwelling predators, such as carabid beetles and spiders, which are rarely found in tilled vegetable crop systems. 
  • Perennial and annual living mulch groundcover in row middles to provide in-field/interspersed plant diversity, season-long pollen/nectar/seed food sources, and winter cover
  • Selective mowing of the perennial living mulch to avoid disturbance of natural enemies at key pest pressure times
  • Irrigation management to discourage certain pests
  • Organic soil amendments to maintain balanced crop growth, thus suppressing insect pests
  • Three-year crop rotation by crop family (Solanaceae, Brassicaceae, Fabaceae)
  • Sprays only when necessary (Table 2): From 1993 through 2000, reduced rates of organic insecticides were applied to avoid killing beneficial insect predators and parasites. No insecticides were applied from 2001 through 2010. Five percent pest damage was tolerated to maintain a food source for natural enemies.
  • Use of selective organic insecticides such as Bt and M-pede (soap)
  • Field scouting of pests, with farm-specific action thresholds
  • Pest-resistant varieties: Red cabbage was more resistant than other brassica crops to aphids and flea beetles at Biodesign.
  • Crop diversification: Solanaceous (60%), brassicas (30%), alliums (5%), other crops (5%)
  • Allowing some crops to mature and flower
  • Allowing certain weeds to grow in the living mulch to provide winter cover, early spring bloom, and summer groundcover for beneficial insects, birds, and fungi
  • Floating and hooped row covers: Used early in the season on brassicas and solanaceous crops for frost control and flea beetle protection
  • Inorganic mulches: Black plastic and paper mulch used in solanaceous crops
  • De facto beetle banks (undisturbed grassy fencerow and pasture) on four margins of both Old and New fields; one 30-ft x 600-ft undisturbed grassy beetle bank in the center of the 5-acre New field
  • 2005–2010, New field: Woody plant hedgerow on the south margin—one 600-foot hedgerow (flowering/fruiting native shrubs and small trees)
  • 2005–2010, New field: Flowering insectary—one 10-ft x 100-ft grass insectary (native, mostly perennial wildflowers) in the center of New field
Outcomes Pest Damage

Crop yield and quality losses to insects mostly decreased over 18 years, according to Helen. This observation is supported by spray records showing reduced use of insecticides 1995- 2000 (Fig. 1). Sprays for aphids, cabbageworms, and Colorado potato beetle were eliminated 2001-2010. Nonetheless, total insect damage to broccoli, cabbage, brussels sprouts, tomato, and pepper crops averaged less than 5% from 2004 to 2010 (Fig. 2 and Fig.5). In contrast, insect damage to unsprayed brussels sprouts in a no-till 2006 experiment averaged 11.5%.

Crop Quality

Biodesign was known at local farmers markets for high-quality tomatoes and peppers. See the eOrganic video: Organic no-till living mulch introduction: Weed Em and Reap.

Lower grade tomatoes and peppers (seconds) were sold by the box at farmers markets for canning. Seconds were small, misshapen, or insect-injured fruits that generally amounted to 5—10% of the total crop yield. Only premium-grade brassica crops were counted in yield/harvest evaluations.

Biocontrol

General field monitoring in Old field (1993–2004) revealed a diversity of beneficial insects, including an abundance of ground-dwelling predators such as ground beetles (Carabidae) and several spider species (Araneae) in the living mulch. See the eOrganic video Organic no-till living mulch beneficials: Weed Em and Reap. On-farm research in 1996 recorded predator incidence in the living mulch, including damsel bugs (Nabidae), syrphid fly adults and larvae (Syrphidae), green lacewing adults and larvae (Chrysopidae), ground beetles (Carabidae), many species of spiders (Araneae), lady beetles (Coleoptera:Coccinellidae), and predaceous stink bugs (Perillus species).

In New field, monitoring from 2004 to 2010 and on-farm experiments in 2006 revealed relatively high season-long diversity and population densities among predator and parasite species (Fig. 3, Fig. 4):

  • Ground-dwelling predators such as carabid beetles (Carabidae) and several spider species (Araneae) were found in high numbers during the growing season, both in the living mulch and under crop plants (Fig. 4).
  • Predaceous stink bugs (Perillus bioculatus and Podisus maculiventris) were prevalent in the later years, feeding on Colorado potato beetle (Leptinotarsa decemlineata) (Photo 1).
  • Several species of syrphid flies (Diptera:Syrphidae) were regulars all season. They seemed to prefer nectar of clover flowers and fanweed (Thlaspi arvense); both occurred in the living mulch in an interspersed pattern between crop rows.
  • Other common generalist predators observed were lady beetles (Coleoptera:Coccinellidae), lacewings (Neuroptera:Chrysopidae), assassin bugs (Reduviidae), nabid bugs (Nabis spp.), and aphid midge (Aphidoletes aphidimyza).
  • Parasites included wasps in the Aphidiidae, Braconidae, and Aphelinidae families. Specific aphid parasitoid wasps were observed attacking several species of aphids (Aphidius and Aphelinus species) and cabbage aphids (Diaeretiella rapae) (Photo 2).

Photo 1. Predaceous stink bug (Perillus bioculatus) attacking Colorado potato beetle larva (Leptinotarsa decemlineata) on Biodesign eggplant leaves. Photo credit: Helen Atthowe.

 

Photo 2. Parasitoid wasps (Aphidius and Aphelinus species) and aphid midge larvae (Aphidoletes aphidimyza) attacking green peach aphid (Myzus persicae) on Biodesign pepper leaves. Photo credit: Helen Atthowe.

Pesticide Applications

Pesticide applications were significantly reduced over 18 years (Fig. 1). Bt-K (Bacillus thuringiensis kurstaki) was sprayed on brassicas for cabbageworms from 1994 through 1998. M-Pede (soap) was sprayed on peppers for aphids from 1995 through 2000. Bt-SD (Bacillus thuringiensis San Diego) was sprayed on eggplant for Colorado potato beetle in 1995 and 1997. No sprays were applied on any crops from 2001 through 2010.

Key Practices Natural Enemy Habitat

Biodesign's solution to insect pest problems was to create interspersed habitat for generalist predators and parasites within crop fields. Knowledge and monitoring of ecological relationships among crops, habitat, and pests were part of the insect pest management system (Table 1).

In the early years (1993-2004), habitat building at Biodesign did not include common strategies such as installed insectary plantings, woody hedgerows, or grassy beetle banks. Instead, the farm was designed as small crop fields bordered on four sides by native grassland/pasture. Cover and food sources for beneficial organisms were distributed within fields and in close proximity to crops, using living mulches, rather than in blocks or rows on field edges.

In 2005, 5 years after pesticide spraying ceased due to decreased pest pressure, Biodesign began to add other habitat-building strategies to New field, including a native plant hedgerow and insectary. See the video Conservation Farming and Sustainability, Missoula, Montana.

Living mulch

Biodesign planted annual living mulches each year from 1993 through 2004. Between 2005 and 2010, perennial living mulches were maintained between crop rows. The living mulch was tilled each spring in Old field. In New field, it was left undisturbed from 2005 through 2010. Living mulches provided the following:

  • Cover and sequential, season-long sources of nectar, pollen, sap, and seed for beneficial organisms. The living mulch bloom sequence extended from early April (fanweed—Thlaspi arvense) through late September (grasses and clover, including flowering white and red clover).
  • Diverse above-ground habitat (different plant heights, flower shapes, and colors)
  • Diverse below-ground habitat (different rooting types and root architecture)
  • Reduced need for tillage
  • Living mulches were 50% of the total area in New field and 30% of the total area in Old field.  During field monitoring, predators and parasites were found within crop rows and in the living mulch between crops.

Certain weeds were left growing in the living mulch to provide winter cover, early spring bloom (Thlaspi arvense), and summer groundcover for beneficial insects, birds, and fungi. A specific weed, Solanum nigrum, was preferred by solanaceous flea beetles at Biodesign and acted as a de facto trap crop.

Species composition

The living mulch was a mixture dominated usually by white clover (Trifolium repens) in Old field and by red clover (Trifolium pratense) in New field. Within 2 or 3 years after first planting in both Old and New fields, the living mulch became a naturally diverse mix of clover, weeds, and grass species that was allowed to flower (Photo 3). Species included:

  • Old field: white clover (Trifolium repens), common mallow (Malva neglecta), chickweed (Stellaria media), pigweed (Amaranthus retroflexus), nightshade (Solanum nigrum), fanweed (Thlaspi arvense), lamb's quarter (Chenopodium berlandieri), prickly lettuce (Lactuca serriola), and purslane (Portulaca oleracea)
  • New field: red clover (Trifolium pratense), fanweed (Thlaspi arvense), lamb's quarter (Chenopodium berlandieri), common mallow (Malva neglecta), white campion (Silene alba), dandelion (Taraxacum officinale), and quackgrass (Agropyron repens)

Photo 3. Flowering weeds in broccoli, such as fanweed (Thlaspi arvense), provided early season nectar and pollen sources for predators and parasites. Photo credit: Helen Atthowe.

Selective mowing

Helen Atthowe's mowing practices evolved since the first living mulch planting in 1993, when she mowed the living mulch regularly to facilitate farm work and reduce competition with crops. Following experiments in 1995 and 1996, she began to let the groundcover grow taller and wilder; beginning in 1998, she allowed the living mulch to flower and produce seed in some rows before mowing.  Helen particularly avoided spring mowing in order to provide wind/cold protection for young crop transplants and to avoid disturbing predators and parasites of green peach aphid. Aphid populations were highest and most damaging to pepper transplants in the spring. Helen also managed the groundcover so that some areas (at least 50%) were undisturbed and blooming throughout the season. See the eOrganic video Organic no-till living mulch mowing: Weed Em and Reap.

Interspersed pattern

Biodesign created mostly interspersed diversification from 1994 through 2010, including living mulches between all crops, partial weediness, and reduced tillage. With interspersed habitat, cover and food sources for beneficial organisms were distributed randomly within and in close proximity to crops, rather than in blocks or rows around crops or on crop edges. Hence predators and parasites did not have to move far from cover and food sources to reach crops. Biodesign also created some aggregated or blocked diversification in New field from 2005-2010, including one non-crop insectary planting and one hedgerow.

Flowering crops

Some crops were allowed to mature and flower each year, particularly brassica crops, which made up about 30% of the cropping area. Broccoli crops usually flowered from July through November (Photo 4).

Photo 4. Mid-season broccoli in full bloom (right) as red cabbage heads begin to size. Photo credit: Helen Atthowe.

Pest-Specific Practices

Table 2 shows strategies, biological control organisms, supplemental pesticides, and outcomes for specific pests.

Aphids

No insecticides were ever applied to manage cabbage aphids. Aphids were a problem and managed with soap (M-Pede) on pepper transplants from 1995 through 2000; high populations occurred where soap was not applied. No insecticides were applied to manage aphids on peppers after 2000, due to low aphid incidence and high numbers of aphid predators and parasites (Photo 2). Nonetheless, pepper yields were stable and/or increased until the farm was sold in 2010 (Fig. 2).

Colorado Potato Beetle (CPB)

CPB feeding on eggplant transplants was a problem in the early 1990s. Field scouting records from July 1996 show CPB present on 48% of eggplant transplants, with an average of 3 larvae and 2 adults per plant (10 leaves each from 10 plants). Adult beetles were hand picked from 1993 through 1996. CPB larvae were sprayed with Bt San Diego in 1995 and 1997. No insecticides were applied to manage CPB after 1997 due to low CPB incidence and high numbers of CPB predators. Natural populations of predaceous stink bugs (Perillus spp.) were observed feeding on CPB in 1996 (Photo 1). Predaceous stink bugs (Perillus bioculatus and Podisus maculiventris) were observed feeding on CPB from 2005-2010. Lady beetles, Carabid beetles and spiders were observed near solanaceous plants during on-farm research in 2006 and 2007.

Flea Beetles (Solanaceous and Brassica)

Flea beetles were occasional problems throughout the 1990s. They were not sprayed, but all brassica and solanaceous transplants were covered with Reemay for 2 to 3 weeks following transplanting from 1993 through 2010 (mostly for frost protection).

Cabbageworms

Bt (Bacillus thuringiensis kurstaki) was applied regularly from 1994 through 1998. Beginning in 1999, no insecticides were applied to control cabbageworms. By 2010, cabbageworms occurred at low levels, likely due to the presence of high numbers of worm predators.

Despite regular (although fluctuating) populations of imported cabbageworm adults, broccoli and cabbage yields were stable from 2004—2008, with less than 5% damage (Fig. 5). During 2006 on-farm research in no-till plots, unsprayed brussels sprouts produced an 88.5% marketable crop, with 0.48 pounds of sprouts harvested per plant (Fig. 6).

Analysis: Integrating Practice and Research Natural Enemy Habitat

In most biologically diverse native plant communities, natural enemies (e.g., insect predators and parasites, microorganisms, birds, and bats) regulate plant pest populations. Diverse plant landscapes, as compared to monoculture agriculture, are correlated with increased diversity and density of biological control organisms (Thies and Tscharntke, 1999).

Systems management for insect suppression aims to reintroduce into farm systems some of the ecological relationships and functions found in undisturbed plant communities. It has been hypothesized that conserved or introduced natural enemies might reduce agricultural insect pests. In some crop/farm systems, natural enemies do provide enhanced pest management (Thies et al., 2003). However, this is not always the case, since pest populations may also respond positively to landscape and farm diversity (Thies et al., 2005).

Using natural plant communities as a model, systems design for economically acceptable insect pest suppression has four components:

  • Learning about the pests and biological control organisms in a particular farm landscape
  • Building and managing habitat to shift the ecological balance toward natural enemies
  • Tolerating low levels of pests in order to support healthy populations of biological control organisms
  • Using selective pesticides only when pest populations exceed the tolerance of farm economics and ecology

Building and managing habitat includes providing food and sheltered areas for biological control organisms to mate, reproduce, and overwinter. Nectar, pollen, sap, and seed are important alternative food sources that fuel predator and parasite survival, flight, and reproduction (Wilkinson and Landis, 2005).

Biodesign built and managed habitat through a variety of practices. The primary long-term strategies included:

  • A diverse perennial and annual living mulch in an interspersed pattern between crop rows to enhance food and shelter for natural enemies. The living mulch was selectively mowed. It occupied 30—50% of the field area and thus may also have interfered with host selection by some insect pests.
  • No-till/reduced tillage
  • Wild margin habitat (native grasslands and pasture)

These practices supported an assemblage of mostly generalist natural enemies that may have contributed to lower pest damage. In 2006 on-farm research, predators and parasites were monitored over the entire growing season using sweep nets and pit-fall traps (Fig. 3 and Fig.4). Biodesign's pattern of interspersed habitat distributed within crops may have been one key to its success. Some evidence indicates that predators and parasites move no more than 60–100 meters from undisturbed habitat into crops (Morandin et al., 2014; Long et al., 1998; Thomas et al., 1991, 1992a, 1992d, 2002). Reduced tillage may also be key because at Biodesign, an undisturbed living mulch in close proximity to crops supported a large population of ground-dwelling predators (Fig.4). This theory is supported by field research in which fewer ground-dwelling predators were found as tillage increased (Halaj et al. 2000, Zehnder and Linduska 1987).

Insect problems and crop damage diminished over time, and Biodesign stopped spraying for insect pests in 2000, with no decrease in crop yields and quality.

Aphids

Specific predators and parasites, such as syrphids, spiders, lady beetles, lacewings, earwigs, parasitoid wasps (Aphidius and Aphelinus species), and aphid midge (Aphidoletes aphidomyza) were observed feeding on aphids at Biodesign (Photo 1) and may have been part of the observed suppression (Fig. 2).

There is support in the literature for these observations. All of these observed predators are listed as aphid predators in the University of California Natural Enemies Handbook (Flint and Dreistadt, 1998). Syrphids were found to be strong aphid predators in an Oregon study (Ambrosino, 2006). Greater vegetation complexity, created by allowing weeds to grow between cabbage rows, was associated with lower cabbage aphid abundance and enhanced populations of generalist natural enemies (Bryant, 2013). Both cabbage and green peach aphid populations were lower on broccoli (Costello, 1994; Costello and Altieri, 1995) and zucchini (Frank and Liburd, 2005; Hooks et al.,1998) where crops were grown with clover living mulches, as compared to clean-cultivated crops.

Colorado Potato Beetle (CPB)

Natural populations of predaceous stink bugs (Perillus species) were observed feeding on CPB in 1996 (photo 2). Predaceous stink bugs (Perillus bioculatus and Podisus maculiventris) were observed feeding on CPB larvae from 2005 through 2010. It has been reported that releases of these predators have suppressed CPB density by 62% (Biever and Chauvin, 1992), reduced defoliation by 86% (Hough-Goldstein and McPherson, 1996), and increased potato yields by 65% (Biever and Chauvin, 1992), when compared to an untreated control (no predator release).

Lady beetles, carabid beetles, and spiders were observed near solanaceous plants at Biodesign from 2005 through 2010. According to some researchers, these predators attack CPB (Hough-Goldstein et al., 1993). Fourteen species of carabid beetles, three species of lady beetles, and one spider species (Xysticus kochi) were reported to feed on CPB (Sorokin, 1976). Adult ground beetles (Lebia grandis) were shown to feed on CPB eggs and larvae, while larvae of the same species parasitize CPB pupae (Weber et al., 2006). Another ground beetle, Pterostichus chalcites, reportedly feeds on CPB (Heimpel and Hough-Goldstein, 1992). The daddy longlegs (Phalangium opilio) has been observed feeding on CPB eggs and small larvae (Drummond et al., 1990). A lady beetle (Coleomegilla maculata) reportedly consumes eggs and small larvae (Groden et al., 1990; Hazzard et al., 1991), killing up to 37.8% of eggs for the first CPB generation and up to 58.1% of eggs of the second generation (Hazzard et al., 1991).

Reduced tillage may have helped to manage CPB. Adult beetles were reduced in no-till tomatoes planted into killed ryegrass compared with tilled tomatoes (Zehnder and Linduska, 1987).

Flea Beetles (Solanaceous and Brassica)

Flea beetles were occasional problems throughout the 1990s in Old field, but were never a problem in New field, where tillage was further reduced and high populations of ground beetles and spiders were observed (Fig. 4). Flea beetles spend a large portion of their life cycle as larvae in the soil and hence may be vulnerable to ground-dwelling predators whose populations diminish with increased tillage. There is some evidence to support this theory. Flea beetle incidence and damage to broccoli foliage was lowest in strip-till/living mulch plots compared to conventionally tilled plots (Luna and Staben, 2000). Ground beetles and spiders reportedly feed on crop pests with subterranean life stages (Brust, 1994; Snyder and Wise, 2001; Halaj and Wise, 2002).

Living mulch row middles at Biodesign, and the reduced tillage they provided, may have enhanced flea beetle predators, especially carabid beetles and spiders. Plant residues increase the density of ground-active predators, both by providing cover on hot days and by providing food for detritus-feeding insects. Spiders and ground beetles in turn feed upon these insects when pests are not available (Settle et al., 1996; Landis et al., 2000; Symondson et al., 2002).

Several studies have demonstrated the negative impact of tillage on pest predators and parasites. Spring cultivation reduced the numbers of one species of carabid beetle (Pterostichus melanarius) by 80% (Cárcamo, 1995). Spider populations declined when fields were tilled (Halaj, 1998). Spider and carabid ground beetle densities increased when conservation tillage practices were adopted (House and Stinner, 1983; Kladivko, 2001; Altieri et al., 2005). Altieri and Gliessman (1983) found that populations of brassica flea beetles were greater in weed-free collard monocultures than in polycultures intercropped with beans and left weedy for 2 or 4 weeks after transplanting.

Cabbageworms

No insecticides were applied after 1999 to control cabbageworms at Biodesign. By that time, cabbageworms occurred at low levels, likely due to the suppressive system and resulting high numbers of worm predators.

Despite regular (although fluctuating) populations of imported cabbageworm adults, less than 5% damage was recorded on unsprayed broccoli and cabbage, and yields were stable over the 15 years of production, even when spraying was stopped after 1999 (Fig. 5). During 2006 on-farm research in no-till plots, unsprayed brussels sprouts produced an 88.5% marketable crop, with 4.8 pounds per plant of salable sprouts (Fig. 6), and large populations of generalist predators were observed in unsprayed treatment plots (Fig. 3) (Fig. 4.)

Possible insect pest suppression due to Biodesign's system strategies is supported by other research. A number of carabid beetles eat imported cabbageworm larvae (Allen, 1979) and reduce lepidopteran pest populations (Brust et al., 1985). The density of all taxonomic groups of soil arthropods, including carabid beetles and spiders, was higher in weedy cropping systems than in conventional tillage systems (McGrath, 2000). More carabid beetles of a specific species (P. melanarius) were caught in plots where brussels sprouts were growing in white clover living mulch than on bare ground (O'Donnell and Coaker, 1975).

Greater vegetation complexity, achieved by allowing weeds to grow between cabbage rows, was associated with lower cabbageworm abundance and enhanced populations of generalist natural enemies (Bryant, 2013). Imported cabbageworm mortality was higher in weedy plots compared to weed-free plots (Dempster, 1969). Cabbageworm egg and larval densities and damage to broccoli at harvest were significantly lower in broccoli undersown with clover living mulches compared to broccoli grown without living mulches and cultivated for weeds, and spider counts were significantly higher on broccoli in living mulch habitats than in cultivated broccoli plots. Despite competition from living mulches, total broccoli yields were not lower in living mulch plots undersown with strawberry clover (Trifolium fragiferum L.) or white clover (Trifolium repens L.). However, yields were lower in yellow sweet clover (Melilotus officinalis L.) living mulch plots when compared to monoculture treatments (Hooks and Johnson, 2007). In two other studies, cabbageworm damage was also lower in crops grown with living mulches (Theunissen, 1994; Brandsæter et al., 1998).

References and Citations
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Additional Resources

This article is part of the Biodesign Farm Organic Systems Description.

Table of Contents:

 

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

eOrganic 15584

Organic Farm System: Biodesign Farm

mer, 2016/09/21 - 14:28

eOrganic authors:

Helen Atthowe, Biodesign Farm

Alex Stone, Oregon State University

Biodesign farmOrganic Farm System: Biodesign Farm System Overview About Biodesign Farm

Farmer: Helen Atthowe

Location: Stevensville, in western Montana (Fig. 1: Area Map)

Crops: Mixed vegetables. Main crops are tomatoes, bell peppers, eggplant, broccoli, cabbage, Brussels sprouts, and winter squash.

Markets: Regional farmers markets (75%) and wholesale to organic supermarkets and restaurants (25%)

Years in organic management: Biodesign began in 1993 and was certified organic with the Montana Department of Agriculture Organic Certification Program until 2008, when the farm joined with other small, local organic producers to form the Western Montana Sustainable Grower's Union. The farm was sold in 2010.

Total farm acreage: 30 acres

Cropped acreage: 8 acres

Landscape design: Two fields—one 6 acres and the other 2 acres. Fields were surrounded by native grassland–sagebrush steppe habitat, several pasture-based cattle operations, and some large-scale potato and small grain producers (Fig. 2: Farm Fields Map). "Old field" (2 acres) was cultivated from 1994 through 2005. In 2006, production moved to "New field" (6 acres).

Regional agricultural production: Ravalli County's 2012 gross agricultural production was $34,725,000, with 70% from livestock production and 30% from crops, mostly grains.

Climate and soils: Semiarid (13 to 16 inches of annual precipitation) with a frost-free growing season of 100 to 115 days. Average last frost is 30 May, and average first frost is 10 September. Spring is the wettest period of the year, with about 25% of annual precipitation falling in May and June. Summer temperatures reach the high 90s, and winter lows are regularly below zero. Soils are classified as capability class VI by the USDA Natural Resources Conservation Service and rated as "poor" for agricultural use (Fig. 2: Farm Fields Map).

Awards: Alternative Energy Resource Organization Sustainable Farm Award, 2000

Farm Philosophy

Rather than treating specific crops, problems, or pests, Biodesign focused on supporting natural nutrient and biological control cycles and on managing ecological relationships.

Key Farm Design and Soil and Habitat Building Strategies
  • Small crop fields embedded in native grass/pasture forest habitat
  • Reduced tillage
  • Perennial and annual living mulch to keep soil covered year-round and to provide winter shelter and interspersed season-long bloom for natural enemies
  • Selective mowing of the living mulch to provide
    • Regular addition of organic residues to the soil/soil microbial community
    • Shade and cooling for crops and beneficial enemies during hot, dry spells. During cool, wet periods, the living mulch was mowed short to enhance drying and increase ambient air temperatures. Following planting, it was left unmowed to provide a windbreak for seedlings and transplants.
  • Compost addition in the early years
  • Gravity-flow irrigation management:
    • Drip irrigation to avoid fruit and foliage wetting (for disease management)
    • Sprinkler irrigation to suppress specific pests such as flea beetles
Soil Management System: Build Soil to Support Natural Nutrient Cycles and Grow High-Yielding, High-Quality, Flavorful Crops

Biodesign's goals were to optimize soil organic matter, reduce tillage, support a diverse soil microbial community, and provide year-round soil cover for natural enemies. The soil management system (Soil Table 1) included:

  • Reduced tillage
  • Perennial and annual living mulches to provide year-round soil cover, with above- and below-ground plant diversity
  • Regular addition of mowed clover/weed soil amendments
  • Annual compost addition most years (1993–2002 on Old field and 2006–2007 on New field)
  • Alfalfa meal addition to crop rows in years when no compost was applied (Disease Table 2 and Table 3).
  • In Old field, soil organic matter (SOM) content climbed from 3.5% in 1993 to 5.7% in 2006, while cation exchange capacity (CEC) increased from 10.2 to 16.8 meq/100g (Soil Fig. 1).
  • In New field, SOM increased from 3.3% in 1993 (when New field was in permanent grass pasture) to an average of  5.2% in 2010 (after New field was cultivated for vegetable production, beginning in 2006). CEC increased from 9.8 to 11.7 meq/100g as SOM increased (Soil Fig. 2).
  • Macronutrients increased while the farm was in production. While some reached excessive levels during the 1990s, almost all eventually reached target levels.

The reduced tillage/living mulch system resulted in good yields of high-quality, flavorful crops and high levels of soil organic matter and soil nutrients. Soil health indicators generally showed positive trends (Soil Table 2).

Read more about the Biodesign soil management system here.

Insect Pest Management System: Maximize Ecological Function and Minimize Off-Farm Inputs

Biodesign's goal was to build and manage habitat for biological control organisms (e.g., insect predators and parasites, birds, bats, soil and foliar microorganisms) and to apply insecticides only when a pest was not sufficiently controlled by the system. Pests were sprayed only when absolutely necessary. The insect pest management system included both systemic practices (Insect Table 1) and pest-specific strategies (Insect Table 2):

  • Landscape-level diversity provided by small crop fields bordered on four sides by native grassland/pasture
  • Reduced tillage
  • Perennial and annual living mulch groundcover in row middles to provide in-field interspersed plant diversity; season-long pollen, nectar, and seed food sources; and winter cover
  • Selective mowing of the perennial living mulch to avoid disturbance of natural enemies at key pest pressure times
  • Irrigation management to discourage certain pests
  • Organic soil amendments to maintain balanced crop growth, thus suppressing insect pests
  • Three-year crop rotation by crop family (Solanaceae, Brassicaceae, Fabaceae)
  • Pesticides were applied only when necessary (Insect Table 2)  and applications ceased in 2000; up to 10% pest damage was tolerated in some crops to maintain a food source for natural enemies.

Crop yield and quality losses to insects decreased from 1993 through 2010, according to Helen. This observation is supported by reduced insecticide use (Insect Fig. 1), crop monitoring records (1993–2010), and on-farm research (2006). Farm records document good yields, less than 3% average crop damage across all crops (Insect Fig. 2 and Insect Fig. 5), and high predator/parasite populations (Insect Fig. 3 and Insect Fig. 4). Aphids on peppers and cabbageworms on brassicas were the main insect pests at Biodesign.

Read more about the Biodesign insect pest management system here.

Disease Management System: Create Conditions Unfavorable for Pathogen Growth

Biodesign's goal was to prevent disease incidence by managing for balanced crop growth and healthy soil, while utilizing good cultural practices such as rotation and irrigation management. The disease management system included both systemic practices (Disease Table 1) and disease-specific strategies (Disease Table 4):

  • Organic soil amendments to maintain balanced crop growth
  • Selective mowing of the between-row living mulch to maximize air flow and leaf and fruit drying
  • Drip irrigation and management to avoid foliar and fruit wetting
  • Three-year crop rotation by crop family (Solanaceae, Brassicaceae, Fabaceae).

Diseases, primarily bacterial speck of tomato (Pseudomonas syringae pv. tomato) and cucumber mosaic virus of pepper (Bromoviridae:Cucumovirus) were never highly damaging due in part to the dry climate. However, losses did occur. Over time, losses declined, especially those caused by bacterial speck as documented by crop quality monitoring records (1993–2010), possibly due to Biodesign Farm's design and soil- and habitat-building practices. Cucumber mosaic virus was observed at low levels on peppers in the early 2000s, but did not become more severe over time or affect crop yield.

Read more about the Biodesign disease management system here.

This article is part of the Biodesign Farm Organic Systems Description.

Table of Contents:

 

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

eOrganic 15582

Biodesign Farm Soil Management System

mer, 2016/09/21 - 14:13

eOrganic authors:

Helen Atthowe, Biodesign Farm

Alex Stone, Oregon State University

This article is part of the Biodesign Farm Organic System Description

Biodesign Farm

Introduction

Biodesign's goals were to optimize soil organic matter and plant nutrient contents, reduce tillage, support a diverse soil microbial community, and provide year-round soil cover for natural enemies.

The farm's native soils are classified as capability class VI by the USDA Natural Resources Conservation Service and rated as "poor" for agricultural use (Overview Fig. 2: Farm Fields Map). Over time, Helen's soil-building system transformed these poor soils into fertile soils with high organic matter content. The fundamental components of the soil management system (Table 1) included:

Outcomes Soil Organic Matter (SOM) and Cation Exchange Capacity (CEC)

Old Field: SOM content increased from 3.5% in 1993 to 5.7% in 2006 (Fig. 1). CEC increased from 10.2 to 16.8 meq/100g during the same period.

In 1993, New field was in permanent grass pasture and SOM was 3.3% (Fig. 2). From 2005 through 2010, New field was cultivated for vegetable production. Low rates of compost (4 and 2 tons/acre, respectively) were applied in 2006 and 2007.  Perennial living mulch residues were mowed and incorporated from 2006 through 2010. By 2010, SOM in New field had increased to 5.2%. Cation exchange capacity (CEC) increased from 9.8 to 11.7 meq/100g during the same period (Fig. 2).

Soil Nutrients and pH

Ongoing soil analyses starting in 1993 indicate that all soil macronutrients—potassium (K), phosphorus (P), calcium (Ca), and magnesium (Mg)—increased. While some reached excessive levels during the 1990s, all were generally at target levels from 2004 through 2010 (Table 2). The exceptions were P in Old field, which remained very high (192 ppm), and soil pH in Old field, which exceeded target levels at 7.6.

Nitrate-Nitrogen, Old Field

Soil nitrate-N levels sampled annually in May increased rapidly as a result of high rates of manure compost application (7–12 tons/acre, 1993–1995) (Fig. 3).  In 1993, nitrate-N was 15 ppm; by 1996, it was 102 ppm, a level considered excessive. Biodesign reduced compost applications to 2 tons/acre from 1999 through 2002 and stopped using manure compost after 2002. Nitrate-N levels decreased from 41 ppm in 2004 to 33 ppm in 2006.

Nitrate-Nitrogen, New Field

Despite reduced rates of high-N amendments such as compost from 2006 through 2010, soil nitrate-N levels in minimum-till crop rows increased from lows of 13 ppm in 1993 to highs of 47 ppm in 2010 (Fig. 4).

In 2006 and 2007, soil nitrate-N was sampled monthly throughout the growing season. Levels of soil nitrate-N were high to excessive every May after incorporation of clover/weed living mulch and compost (Fig. 5).  During the main crop growing season, nitrate-N decreased but remained relatively high (23–75 ppm). In the fall, it decreased to 30 ppm on average.

Potassium (K)

Over the years of annual manure-based compost application, K levels increased in Old field from 145 ppm in 1993 to 713 ppm in 2003. Potassium decreased to 323 ppm after Biodesign stopped manure compost application. In New field, rates of manure compost application were lower (2-4 tons/acre), and soil K never reached the high to excessive levels recorded in Old field.

Phosphorus (P)

Phosphorus levels increased steadily in Old field (from 9 ppm in 1993 to 192 ppm in 2006), even after Biodesign stopped manure compost application. In New field, rates of manure compost application were lower (2-4 tons/acre) and soil P never reached the high levels recorded in Old field.

Soil pH

In Old field, soil pH increased from 6.9 in 1993 to 7.7 in 1999, during the period of time when Biodesign added large amounts of manure-based compost (Fig. 6). Potassium also reached excessive levels over this period. As manure application and K levels decreased, pH decreased only slightly to 7.6 (2004–2006). Despite the high pH, yields and crop quality were very good in Old field (see video Organic No-Till Living Mulch Intro: Weed Em and Reap).

In New field, where lower rates of manure compost were applied and K levels never became excessive, soil pH remained relatively stable (around 6.8). Soil analysis was not performed regularly in New field until the field was tilled/cover-cropped in 2005 to prepare for vegetable production in 2006.

Crop Quality and Yield

Biodesign was known at farmers markets for high-quality peppers and tomatoes, disease and insect damage to crops was low. Over time, crop quality increased. According to Helen, crops seemed to be more resistant to frosts and sunscald (pepper) and to store better, especially red bell peppers and winter squash. Blossom end rot of tomatoes was a minor problem in the mid-1990s, but was not a problem after 1999.

Yields from Old field were excellent in the late 1990s and early 2000s. Total yields decreased slightly once Biodesign moved exclusively to New field and began experimenting with wider permanent clover row middles. While wider living mulch rows decreased the area per acre in commercial crops, this loss was offset by reduced production costs with decreased need for labor and fertilizer/pest management inputs. Biodesign reduced, then eliminated, manure-based compost additions in New field.

Key Practices Living Mulch and Organic Residues

From 1993 through 2010, Biodesign's system evolved towards less tillage, fewer manure-compost amendments, and more plant-based soil amendments. Biodesign applied several kinds of organic residues throughout the year, both incorporated and surface applied. Organic residues applied were:

  • Incorporated living mulch each spring (April)
  • Mowed living mulch throughout the growing season
  • Incorporated on-farm compost
  • Alfalfa meal additions to crop rows in years when no compost was applied 

Living Mulch (Annual and Perennial)

Old Field: From 1993 through 2004, Biodesign experimented with annual living mulches. In early spring, clover (usually white clover, Trifolium repens) was planted between 48-inch crop rows or beds. Clover was left undisturbed during the growing season and through the winter. The living mulch was mowed two to four times each growing season to control annual weeds and to cycle residues back into the soil. Before each mowing, the living mulch ranged from 8 to 18 inches tall. Soil cover was greater in the winter because the living mulch grew into crop rows and beds over the growing season and into the fall.

The following spring, clover row middles were tilled and incorporated into the soil; they then became the planting beds for the next growing season. A new clover cover crop was seeded between the new crop rows. This system provided alternating strips with clover cover 11 months of the year and an incorporated “green manure” clover strip each spring. For a video of the Old field system, see Living Mulch Part 1: Weed Em and Reap.

New Field: In 2005, Biodesign moved to a new 6-acre field and began to experiment with less tillage and permanent perennial living mulch row middles. Wider rows permitted mowing with a tractor rather than a hand mower. The 48-inch crop beds were tilled minimally each spring while the permanent living mulch row middles were not tilled. At least 50% of the field was covered with growing clover/weed roots year-round. The living mulch was mowed two to four times annually when the living mulch was 8 to 18 inches tall. Because the perennial clover living mulch grew slowly back into crop rows over the growing season and into the fall, when crop rows were tilled each spring, clover/weed “green manure” was incorporated into the soil every April. In 2006, all crop rows were covered with red clover planted in 2005 which was incorporated in April 2006. From 2007-2010, some new perennial red clover areas in the New field were “strip-tilled” and brought into new vegetable rows. For a video of this system, see Conservation Farming and Sustainability, Missoula, Montana.

Biodesign's living mulch system was designed to:

  • Slowly cycle and recycle plant nutrients by regular mowing and surface application of mowed residues. On average, approximately 1 to 1.5 tons/acre of legume hay mulch (dry weight) was added to the soil surface each year in the Old Field and approximately 1-2 tons/acre of legume hay added in the New field (due to greater area in row middle).
  • Provide growing roots and winter cover, reduce erosion by wind and water, reduce surface compaction, and reduce the effects of winter freeze/spring thaw cycles and heavy spring rainfall on bare soils.
  • Provide N for the following crop. Leguminous living mulches provided significant amounts of N, especially when they were incorporated each spring; when clover living mulch foliage was tested prior to mowing during the growing season, above-ground plant biomass averaged 4% N (Table 3).
  • Improve soil physical properties. Growing roots of the living mulch and incorporated or surface-applied residues seemed to improve drainage and tilth over time, allowing Biodesign to get into wet fields earlier in the spring.
  • Sequester N in plant biomass to help prevent N leaching. According to a Biodesign living mulch nutrient analysis in 1996, the living mulch contained good levels of nutrients, including N, P, and K in September (Table 3).

Weeds were allowed and sometimes encouraged in the living mulch to build habitat for natural enemies. In the New field, weeds provided diverse annual and perennial species with different rooting types and depth and different plant families (Table 4).  In the Old field, Helen tolerated common mallow (Malva neglecta) due to its reported high soil nutrient contribution. See the eOrganic Weed Em & Reap video: Organic No-Till Living Mulch Weed Ecology and the video Winter Annuals as a Living Mulch-Pennycress. Some nutrient cycling likely occurred as weeds were mowed and incorporated.

Despite their proliferation in the living mulch, weeds did not become problematic at Biodesign. Most crops were transplanted onto raised 48-inch beds rather than seeded. Black plastic mulch was used with warm-season crops (tomatoes, peppers, and eggplants). From 1993 through 1996, black plastic was also used with cool-season transplants. Living mulch row middles were mowed regularly in the summer to manage weeds and keep weeds from going to seed. Seeded crops such as lettuce, beets, carrots, parsnips, and beans were hand weeded once or twice per season. The living mulch weed management system reduced and, with some crops, eliminated the need for mechanical cultivation and hand weeding. The following changes in weed ecology were noted:

  • Old field: Common mallow (Malva neglecta) became dominant over time. Other more common weeds, such as pigweed (Amaranthus retroflexus) and lamb's quarter (Chenopodium album), were common in the early 1990s, but decreased significantly.
  • New field: As a result of the permanent red clover living mulch row middles, there were no weed problems for the first 3 or 4 years. After that time, rhizomatous grasses began moving into permanent clover row middles. By 2010, smooth brome (Bromus inermis) was dominant in row middles and required management (tillage in 2011) because it became too competitive with crops.
Compost

Compost was made on the farm, using oat or wheat straw, clover, and sheep or cattle manure from neighboring farms. Find the compost nutrient content in Table 5 and find composting details by watching the video Organic No-Till Living Mulch Composting: Weed Em and Reap.

Old field: Every spring until 2003, compost was added to the entire field with a Case manure spreader (Disease Table 2). Compost was incorporated along with the clover living mulch. No compost was added from 2003 through 2006. Compost was made on the farm with sheep and/or cattle manure, straw, and mowed clover residue. In the 1990s, Helen used Luebke's Controlled Microbial Composting (CMC) techniques for compost production and quality evaluation.

New field: In 2006 and 2007, compost was added mainly to the 48-inch crop beds with a Case manure spreader. Avoiding compost application to living mulch row middles likely increased the rate of compost application in crop rows. Though compost was applied at 4 tons/acre (2006) and 2 tons/acre (2007) rate, in-crop-row compost application rates  may have been higher in some areas. It was difficult to precisely apply low rates of compost to crop rows only with the available equipment. In the spring of 2006, clover living mulch was incorporated along with compost in crop rows only. In 2007 through 2010, the perennial clover grew back into crop rows and beds during the growing season, fall, and early spring and was incorporated into the soil every April (Disease Table 3). New rows were brought into cultivation 2007-2010 from untilled red clover areas in New field. From 2008-2010 clover was incorporated, but no compost was added to crop rows. 

Supplemental Amendments

From 2008 through 2010, alfalfa meal was spread in crop rows (New field) and incorporated in the spring before planting along with some clover/weed living mulch that grew into crop rows (Disease Table 3). Rates were approximately 50 lb/4-ft x 600-ft row. Alfalfa meal was spread by hand, using a pickup truck driving on living mulch row middles and straddling crop beds. According to Parnes (1990), alfalfa meal has a reported nutrient content of 2.7% (N), 0.5% (P), and 2.8% (K).

Gypsum was hand applied to New field crop rows in 2007, at 100 lb/4-ft x 600-ft row.

Reduced Tillage

Tillage is an important part of many organic farming systems that utilize organic residues for soil fertility management. In annual horticultural systems, tillage is also utilized for weed management. However, primary tillage was greatly reduced at Biodesign, and tillage for weed management was eliminated.

Old field: From 1994 through 1999, tillage was done with a 6-ft rototiller. In 1999, the rototiller was sold. A potato cultivator was modified for primary tillage; after primary tillage, crop beds were tilled with a 3-ft rototiller.

New field: Strip tillage was done in 4-ft beds. Four-foot-wide permanent living mulch row middles were left untilled. Primary tillage equipment included a single shank chisel plow/ripper followed by a 3-ft rototiller.

Biodesign evolved toward less and less tillage over time, based on observations that competition from the living mulch did not seem to reduce yields economically and soil and crop quality seemed to improve. Further impetus was results of on-farm research (2005), which showed a slight reduction in SOM two weeks after the 60-year-old pasture was tilled in (Table 6).

Analysis: Integrating Practice and Research

The goal of an organic soil management system is to build SOM and enhance soil microbial activity, rather than to rely on quick-release fertilizers to directly feed crops. Decomposition, mineralization of plant-available nutrients, and nutrient retention are the foundations of soil ecosystem functions on organic farms. As organic matter decomposes, nutrients such as N, P, and K are mineralized and made available to plants.

Soil microbes play a role in all of these processes (Kramer, 2006). In turn, soil microbial biomass and activity are regulated by the quantity and quality of SOM, carbon (C), and N inputs (Fierer et al., 2009; Kallenbach and Grandy, 2011). Research has shown that total C content (Drinkwater, 1998; Kong, 2005) and/or lability (ease of decomposition) of organic matter (Marriott and Wander, 2006; Smukler et al., 2008; Kallenbach and Grandy, 2011) determine how organic amendments will affect microbial biomass by affecting the rate of decomposition and N mineralization. Materials with higher C content tend to decompose more slowly, thus releasing N slowly over the season.

Organic amendments such as manure, grass and/or legume cover crops, mulches, and compost vary in C content and C:N ratio. Therefore, they vary in their rate of decomposition and in how they stimulate microbial biomass.

When Biodesign began in 1993, Helen’s main concern in Montana's cold-spring climate was how to get enough N and P into crops for good yields and early maturity at farmers markets. Over time, her primary challenge became how to manage too much N, P, and K in the system and how to move towards higher C soil amendments. Through on-farm research, Biodesign investigated how to manage organic residues in a way that would provide enough nutrients for good and early yields, while linking N and P mineralization to SOM decomposition to avoid excessive levels. Biodesign's nutrient cycling system worked in a synergistic manner with its biological insect management system.

Nitrogen Cycling System

Biodesign’s system evolved in three phases:

  1. In 1994 and 1995, Helen assumed she would need to supply a considerable amount of nutrients, based on soil class information and on 1993 soil tests. Helen added N based on her nutrient replacement calculations.
  2. In the late-1990s, with more experience using reduced tillage and living mulches, as well as annual May soil test records, Helen felt that fertility, particularly N and K, was present in adequate, even excess supply, so she decreased manure compost application rates with the goal of decreasing N, P, and K soil levels.
  3. By 2005, with information from 11 years of soil tests and yield records, Helen moved towards a system with greater tillage reduction, increased space between crop rows, lower application rates of manure compost, and greater reliance on higher C plant residue soil amendments.

Each year, soils were tested in May after April incorporation of living mulch and sometimes compost. Helen used these soil analyses and a nutrient replacement calculation to calculate how much N she needed to apply. She assumed that annual vegetable crops generally remove approximately 150 lb N/acre. As Biodesign's system evolved, sources of N were:

  • Organic residues—incorporated and mowed living mulch (Table 3), compost (Table 5), and alfalfa meal
  • Residual soil nitrate-N (nitrate pool) (Fig. 3 and Fig. 4).
  • Mineralization of N from SOM (assumed to be approximately 30 to 60 lb N/acre over a 60-day period in the summer)
  • Irrigation water (Table 7)

Over time Biodesign observed the following outcomes:

  • Soil contained high levels of N, P, K, Ca, and Mg (Table 2).
  • N and other nutrients were released relatively quickly in the spring after incorporation of organic residues, then appeared to be released more gradually over the growing season, possibly from the reservoir of SOM.
  • No post-plant, side-dress fertilizer was needed or applied.
  • The microbial community was relatively high in no-till living mulch row middles, even when crop row tillage decreased microbial populations, particularly arbuscular mycorrhizae.

Key to Biodesign’s nitrogen cycling system was reduced tillage and regular addition of organic plant residues (mowed legume living mulch) with differing C:N ratios during the growing season, rather than simply relying on compost/green manure incorporation into the soil once every spring. Biodesign’s goal was to match N mineralization with crop demand and achieve a more idealized “steady-state condition”, in which organic N concentrations remain relatively constant in the soil. Even though this approach is likely to be superior to “discrete manure spreading events”, nutrient levels are hard to predict because N mineralization rates can vary considerably with moisture and temperature (Crohn, 2004) and plant maturity which is often expressed in terms of C:N ratios and lignin content (Fox et al., 1990). The C:N ratio of Biodesign’s mowed living mulch residue when tested in 1996 was highest in July and lower in August and September (Table 3).

Soil nitrate-N: Nitrogen mineralization appeared to be relatively rapid at Biodesign; levels of nitrate-N in Biodesign soils were high to excessive every May when soils were tested within 2-3 weeks after incorporation of living mulch and compost or living mulch/alfalfa meal in April (Figure 3 and Figure 4).  During on-farm research studies in 2006 and 2007 Helen sampled soil N levels monthly throughout the growing season in an effort to understand what was the contribution of incorporated residues and mowed living mulch residues to soil nutrient availability. Nitrogen in her “standard-practice” minimum-till crop rows decreased but remained relatively high (24-75 ppm) during the main crop growing season (June–August); N levels decreased in September to 31 ppm (2006) and 28 ppm (2007) (Figure 5).  However, in no-till crop rows, where organic residues were not incorporated into the soil and clover living mulches grew back into crop rows over the season, N levels were lower (16-47 ppm) during the cropping season and dropped in September to 10 ppm (2006) and 20 ppm (2007) (Figure 5).

Untilled living mulches reportedly absorb a large percentage of residual soil N (65–70%) and sequester it in plant biomass during the winter and in the spring when leaching rains may occur (Smith, 2007). Another observation from Biodesign’s soil test records may further support the N recycling/sequestering potential of no-till living mulches between crop rows; soil nitrate-N levels were lower in no-till living mulch rows than in crop rows and also decreased temporarily after perennial living mulch row middles were mowed in the summer. According to results from an on-farm study in 2006, August nitrate-N levels were lower in mowed verses un-mowed sections of a 600-ft no-till living mulch row middle (Figure 11). This could be due to temporary immobilization of N as a result of microbial activity during decomposition of mowed residues. Microbial activity appeared to be high in untilled living mulches when tested at Biodesign. Denitrification from surface-applied living mulch may also have occurred.

Soil microbial activity: Total microbial biomass (TMB) was measured in early June during 1996 on-farm research. TMB levels were relatively high in untilled living mulch plots (528 ppm) and much lower in tilled plots (345 ppm). Microbial activity and N retention may have remained high due to reduced tillage and annual application of organic residues (Calderón et al., 2000; Minoshima et al., 2007; Jackson et al., 2012). In 2007 on-farm research at Biodesign, arbuscular mycorrhizae were lower in tilled plots than in no-till plots (Figure 12).

Biodesign’s good and early crop yields from 1994-2010 indicate that sufficient N levels were available for crop growth. In California, on-farm research suggests that a soil nitrate-N level of 20 ppm or greater is sufficient to maintain maximum vegetable crop growth rates for several weeks or more in typical field conditions (Smith, 2007). Smith (2007) also suggests that spring vegetable crops usually have higher N fertilizer requirements because soil N is lower due to leaching of residual soil nitrate in the winter and low soil microbe activity in cooler spring soils.

Nitrate leaching at Biodesign appeared to be relatively low according to well water analysis in 2000 and 2010, which recorded safe levels of nitrate-nitrogen.

Phosphorus

In Old field, P increased steadily from a low of 9 ppm in 1993 to a high of 192 ppm in 2006 ppm, even after Biodesign reduced and stopped manure compost application. However, with lower rates of manure compost application, levels of soil P in New field never reached the high to excessive levels recorded in the Old field.

Potassium

In Old field, K increased sporadically from 145 ppm in 1993 to 713 ppm in 2003 during the time that Biodesign applied manure-based composts annually, and decreased to 323 ppm when Biodesign reduced and stopped manure compost application. However, with lower rates of manure compost application, levels of soil K in New field never reached the high to excessive levels recorded in the Old field.

Soil pH

In Old field, the pH increased from 6.9 in 1993 to 7.7 in 1999, during the time that Biodesign was adding larger amounts of manure-based compost and potassium reached excessive levels in the soil; the pH decreased only slightly to 7.6 (2004–2006) as manure applications and potassium levels decreased. Despite the high pH, yields and crop quality were very good in Old field. In New field, where lower applications of manure compost were applied and potassium levels never reached excessive levels, soil pH remained relatively stable around 6.8. Soil tests were not taken regularly in New field from 1996–2004 until the field was tilled to prepare it for vegetable production in 2005.

References and Citations
  • Calderón, F. J., L. E. Jackson, K. M. Scow, and D. E. Rolston. 2000. Microbial responses to simulated tillage in cultivated and uncultivated soils. Soil Biology and Biochemistry 32: 1547–1559. (Available online at: http://www.ucanr.org/sites/ct/files/44358.pdf) (verified 22 Dec 2015)
  • Drinkwater, L. E., and P. Wagoner. 1998. Legume-based cropping systems have reduced carbon and nitrogen losses. Nature 396: 262–265. (Available online at: http://www.nature.com/nature/journal/v396/n6708/abs/396262a0.html) (verified 22 Dec 2015)
  • Fierer, N., M. S. Strickland, D. Liptzin, M. A. Bradford, and C. C. Cleveland. 2009. Global patterns in belowground communities. Ecology Letters 12: 1238–1249. (Available online at: http://onlinelibrary.wiley.com/doi/10.1111/j.1461-0248.2009.01360.x/abstract) (verified 22 Dec 2015)
  • Jackson, L. E., T. M. Bowles, A. K. Hodson, and C. Lazcano. 2012. Soil microbial-root and microbial-rhizosphere processes to increase nitrogen availability and retention in agroecosystems. Current Opinions in Environmental Sustainability 4: 517–522. (Available online at: http://www.sciencedirect.com/science/article/pii/S1877343512000991) (verified 22 Dec 2015)
  • Kallenbach, C., and A. S. Grandy. 2011. Controls over soil microbial biomass responses to carbon amendments in agricultural systems: A meta-analysis. Agriculture, Ecosystems and Environment 144: 241–252. (Available online at: http://pubpages.unh.edu/~asf44/files/kallenbach_and_grandy_2011.pdf) (verified 22 Dec 2015)
  • Kong, A.Y.Y., J. Six, D. C. Bryant, R. F. Denison, and C. van Kessel. 2005. The relationship between carbon input, aggregation, and soil organic carbon stabilization in sustainable cropping systems. Soil Science Society of America Journal 69: 1078–1085. (Available online at: http://www.plantsciences.ucdavis.edu/vankessel/publications/bryant_et_al.pdf) (verified 22 Dec 2015)
  • Kramer, S. B., J. P. Reganold, J. D. Glover, B.J.M. Bohannan, and H. A. Mooney. 2006. Reduced nitrate leaching and enhanced denitrifier activity and efficiency in organically fertilized soils. Proceedings of the National Academy of Sciences of the United States of America 103: 4522–4527. (Available online at: http://www.pnas.org/content/103/12/4522.full) (verified 22 Dec 2015)
  • Marriott, E. E., and M. Wander. 2006. Qualitative and quantitative differences in particulate organic matter fractions in organic and conventional farming systems. Soil Biology and Biochemistry 38: 1527–1536. (Available online at: http://www.sciencedirect.com/science/article/pii/S0038071706000022) (verified 22 Dec 2015)
  • Minoshima, H., L. E. Jackson, T. R. Cavagnaro, S. Sánchez-Moreno, H. Ferris, S. R. Temple, S. Goyal, and J. P. Mitchell. 2007. Soil food webs and carbon dynamics in response to conservation tillage in California. Soil Science Society of America Journal 71: 952. (Available online at: https://dl.sciencesocieties.org/publications/sssaj/abstracts/71/3/952) (verified 22 Dec 2015)
  • Parnes, R. 1990. Fertile soil: A grower's guide to organic and inorganic fertilizers. agAccess, Davis, CA
  • Smith, R. 2007. Farm water quality planning project. PowerPoint presentation. University of California Cooperative Extension/USDA Natural Resources Conservation Service. (Available online at: http://cemonterey.ucanr.edu/files/85240.pdf) (verified 28 Dec 2015)
  • Smukler, S. M., L. E. Jackson, L. Murphree, R. Yokota, S. T. Koike, and R. F. Smith. 2008. Transition to large-scale organic vegetable production in the Salinas Valley, California. Agriculture, Ecosystems and Environment 126: 168–188. (Available at: https://ucanr.edu/repositoryfiles/Agriculture,%20Ecosystems%20and%20Environment-93570.pdf) (verified 22 Dec 2015)
Additional Resources

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

eOrganic 15625

Management Options for Striped Cucumber Beetle in Organic Cucurbits

jeu, 2016/09/15 - 18:05

Join eOrganic for a webinar on management options for striped cucumber beetle on organic farms by Abby Seaman and Jeffrey Gardner of Cornell University. The webinar takes place on Wednesday, January 11, 2017 at 2PM Eastern (1PM Central, 12PM Mountain, 11AM Pacific Time).

Striped cucumber beetle (SCB) is one of the most challenging insects to control in organic cucurbit production. The presenters will discuss the basics of SCB biology, cultural practices that can minimize damage, the latest on the effectiveness of insecticides allowed for organic production, and a discussion of breeding work underway to help reduce beetle impact.

Register now at https://attendee.gotowebinar.com/register/7716979911488393475

This webinar was organized by members of the NIFA-OREI funded Eastern Sustainable Cucurbit Project, which is a collaboration of growers, researchers and extension agents working to find solutions for the many challenges facing organic cucurbit producers. Find more webinars by this project here in the eOrganic webinar archive at http://articles.extension.org/pages/25242

Presenters: Abby Seaman, New York State IPM Program; Jeffrey Gardener, Entomology Department, Cornell University

System Requirements

View detailed system requirements here. Please connect to the webinar 10 minutes in advance, as the webinar program will require you to download software. To test your connection in advance, go here. You can either listen via your computer speakers or call in by phone (toll call). Java needs to be installed and working on your computer to join the webinar.  If you are running Mac OSU with Safari, please test your Java at http://java.com/en/download/testjava.jsp prior to joining the webinar, and if it isn't working, try Firefox or Chrome.

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

eOrganic 20556

Farm Case Studies

mer, 2016/09/14 - 16:00

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

eOrganic T1227

Incorporating High Tunnels into a Diversified Organic Vegetable Farm in Oregon: Case Study of Gathering Together Farm

mer, 2016/09/14 - 15:44

eOrganic authors:

Galen Weston, Tuolumne River Trust

John Eveland, Gathering Together Farm

Jolene Jebbia, Gathering Together Farm

Alex Stone, Oregon State University

Introduction

In a collaboration between Gathering Together Farm (GTF) and Oregon State University (OSU), three high tunnels (Haygroves) were constructed side by side in January of 2003 on site at GTF. For the last three years, data has been collected in order to analyze high tunnel performance within the context of a diversified organic vegetable farm.

Gathering Together Farm is a 40 acre organic farm in the Willamette Valley that markets produce through a CSA, farmers markets, and direct sales to restaurants. When the high tunnels were constructed in 2003, GTF had 11 smaller greenhouses in use totaling 25,000 square feet. This report summarizes the experiences of the farmers over the three year trial.

Three high tunnels at Gathering Together Farm, Philomath, Oregon. Photo credit: Galen Weston, Tuolumne River Trust

History of High Tunnels at GTF

In January of 2001, 5 GTF employees spent 2 full days constructing the three tunnels. In the first growing season, High Tunnel 1 (HT 1) was used for 3 beds of potatoes planted February 15, and two beds of tomatoes planted April 4. High Tunnel 2 (HT 2) contained 1.5 rows of both peppers and eggplants planted May 1, 1 row of basil planted April 20 and 2 rows of zucchini planted April 20. High Tunnel 3 (HT 3) contained 1.5 rows of cucumbers planted June 1, 2.5 rows of tomatoes planted June 1, and 1 row of okra planted June 1.

In 2004, HT 1 was home for 2.5 rows of tomatoes, 2 rows of zucchini, and 0.5 rows of basil all planted on April 25. HT 2 contained salad mix sown in mid February, followed by 2 beds of peppers planted May 1, 1 bed of eggplant planted May 1, 0.5 bed of hot peppers planted May 1, 1 bed of cucumbers planted in June, 1 bed of late basil planted at the end of August, and 1 bed of okra planted June 1. Half of HT 3 was planted to early carrots on February 5 and potatoes in February 5. On June 1, storage tomatoes were planted following the carrots.

In 2005, each tunnel had an early and late crop. HT 1 was seeded with salad mix in mid February, which was harvested during the month of April. Following the salad mix crop, 2 rows each of zucchinis and peppers and 1 row of eggplant were transplanted. In HT 2, carrots were sown on January 9 and again on February 9th. One bed each of peppers and eggplants were transplanted following the potatoes and 3 beds of storage tomatoes were planted on June 1st following the carrots. In HT 3, 2 beds of endive and 3 beds of head lettuce were transplanted on February 20th. Following the lettuce harvest in mid April, 1 bed of basil and 4 beds of tomatoes were transplanted.

Harvesting Salad Mix (4/18/05). Photo credit: Galen Weston, Tuolumne River Trust

Farmer Observations

According to farmers John Eveland and Jolene Jebbia, the most significant attributes of the high tunnels are their large size and their capacity for excellent ventilation. For GTF, the most serious limitations to the length of their growing season are wet soil conditions that prevent mechanical bed preparation and planting in the spring; and pest and disease pressure resulting from cold, wet conditions in the fall.

Together, the three tunnels keep a total of 18,000 square feet dry and their size permits easy access for most farm implements. The large size of the tunnels also makes them more suitable for sprawling crops such as zucchini that had previously been impractical for greenhouse culture. By keeping the soil dry through the winter and thus available to be tilled at the farmer’s discretion, the tunnels allow for earlier plantings and more diverse rotations. Another factor influencing early spring plantings is the difficulty in managing weeds because wet conditions in the fields are unsuitable for mechanical cultivations. The crops grown in tunnels avoid this problem and allow GTF to maintain a cultivation schedule regardless of outside weather.

By having adjustable side walls, the farmers are able to manage the humidity and airflow within the tunnels thus reducing disease and pest pressure. The dry, well ventilated climate of the tunnels is often superior to conditions in the field and in other greenhouses. In previous years, late plantings of carrots were often decimated by the larvae of the carrot rust fly which thrive in wet soil. However, by growing carrots within the relatively dry tunnels, GTF has been able to extend its carrot harvest by one month into the late fall. Compared to other GTF greenhouses, John Evelend observed that the ventilation options in the high tunnels were superior for later plantings of tomatoes because the farmers were able to create cooler night temperatures and thereby produce hardier plants.

From left to right: February planted potatoes, January sown carrots, February sown carrots, workers harvesting salad mix. (4/18/05) Photo credit: Galen Weston, Tuolumne River Trust

The size of the tunnels and their ventilation options do have a downside. The tunnels have proved less suitable than other greenhouses at GTF for the earliest plantings of tomatoes because they are less efficient at maintaining the relatively high temperatures required by that heat loving crop.

Due to the benefits associated with the tunnels, GTF now grows 7 crops in greenhouses that it previously had planted solely in the field: peppers, eggplants, basil, potatoes, head lettuce, zucchini and carrots. Compared to field culture, tunnel culture has extended the harvest window of these crops both early and late in the season.

This greatly expanded winter/early spring selection of vegetables has had a significant economic impact on GTF. Table 1 shows how much additional yield the tunnels made possible during 2004 and indicates a $29,000 contribution to the farm budget. GTF maintained 5 more restaurant contracts in the winter of 2004-2005 than in previous years and also significantly increased the variety in their winter CSA offerings.

Estimate of high tunnel impact on 2004 farm profits. Crops Weeks Early Weeks Late Total Additional Yield Price/Unit Gross Profit Peppers 3   150 lbs $2.00/lb $300 Eggplant 4   100 lbs $2.50/lb $250 Basil 3 3 1100 bunches $2.00/bunch $2,200 Potatoes 12   600 lbs $1.50/lb $900 Carrots 6   500 bunches $2.00/bunch $1,000 Lettuce 4 4 2500 heads $1.25/head $3,125 Zucchini 3   450 lbs $2.00/lb $900 Mesclun     300 lbs $7.95/lb $2,385 Tomatoes   4 9000 lbs $2.00/lb $18,000       Gross Additional Income   $29,060 Conclusions

Prior to 2003, the limited greenhouse space at GTF only allowed for a simple rotation of salad mix followed by either cucumbers or tomatoes. Now, the tunnels complement the GTF production strategy and ensure a significantly increased selection of fall and spring crops. In January, the smaller greenhouses are sown to salad mix while the tunnels are planted to early crops of salad greens, potatoes, and carrots throughout January and February. Following the harvest of the earliest salad mix, the first plantings of tomatoes and cucumbers go into the smaller greenhouses. Following the spring tunnels crops, late plantings of summer solanaceous crops perform better in the well ventilated tunnels than in the smaller greenhouses and last longer than solanaceous crops planted unprotected into the field.

The result of this well planned rotation is a significantly larger harvest occurring over many more weeks of the year. While the tunnels are a central component of this expanded rotation, the farmers at GTF would not recommend tunnels as a replacement for other greenhouses. Rather, they view them as a complementary tool which greatly increases the versatility of a season extension strategy for fresh market growers. For information on how other organic farmers use high tunnels in vegetable production systems, see eOrganic article High Tunnels on Organic Vegetable Farms: Case Studies

References and Citations

 

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

eOrganic 2775

Weed Management Case Study, Quiet Creek Farm, Kutztown, PA. Penn State Extension Start Farming Video

mer, 2016/09/14 - 15:42

Penn State Extension Start Farming Farm Profiles Series: Weed Management.

John and Aimee Good run a 200 member CSA on 8 acres of land leased from the Rodale Institute in Kutztown, PA. In this video, John Good discusses weed management practices on their farm.This series of videos is designed to give new farmers ideas and advice from experienced producers.

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This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

eOrganic 7586

Organic Vegetable Farms in New England: Three Case Studies

mer, 2016/09/14 - 15:38

eOrganic author:

Kim Stoner, The Connecticut Agricultural Experiment Station

Source:

Stoner, K., S. Gilman, S. Vanek, B. Caldwell, C. Mohler, M. McGrath, D. Conner, A. Rangarajan. 2008. Organic vegetable farms in New England: three case studies [Online]. Connecticut Agricultural Experiment Station Bulletin 1021. Available at: http://www.ct.gov/caes/lib/caes/documents/publications/bulletins/b1021.pdf (verified 4 March 2010).

This article introduces three NEON Project farms that are more fully described in the source bulletin. This article also provides links to farm photo galleries and a more detailed case study of New Leaf Farm (see below).

Kestrel Farm, Tom Harlow, Westminster VT

Tom Harlow produces sweet corn, lettuce, and winter storage vegetables, primarily for wholesale markets on his 50 cultivated acres. He identifies his crop mix, particularly the emphasis on winter storage crops, as critical to Kestrel Farm’s success. His crop mix allows him to spread labor, marketing, and cash flow over the year, and to reach out to wholesale markets over a large area. Another key feature has been his ability to recruit and keep skilled labor over several years in a difficult labor market. The labor supply is a concern for the long-term future, as is true for many farmers. His network of family, neighboring farmers, markets, and truckers is another critical factor, and the nearly ideal combination of deep, level, fertile, well-drained soils and abundant water for irrigation supports the production capacity of the farm. Focal Crops studied: lettuce, parsnips, butternut squash.  Image gallery of Kestrel Farm by the NEON Project.

farmer Tom Harlow

Farmer Tom Harlow. Photo credit: Kim Stoner, Connecticut Agricultural Experiment Station

Parsnip field at Kestrel Farm after cultivation between the beds

Parsnip field at Kestrel Farm after cultivation between the beds. Photo credit: Kim Stoner, Connecticut Agricultural Experiment Station

Upper Forty Farm; Kathy, Ben, and Andy Caruso; Cromwell CT

Kathy Caruso’s dedication to finding, growing and marketing a huge diversity of the most flavorful and interesting vegetable varieties at upscale farmers’ markets in Connecticut is critical to the economic success of this farm, despite some production problems related to poor soil drainage. The Caruso family produces 99 varieties of tomatoes, 35 varieties of hot peppers, 18 varieties of potatoes, and successive crops of specialty snap beans, early season fava beans and, later in the year, edamame (edible soybeans) on only 3.5 cultivated acres. Focal Crops: snap beans, tomatoes, butternut squash.  Image gallery for the Upper Forty Farm by the NEON Project.

Farmer Kathy Caruso with a friend working at a farmer's market

Farmer Kathy Caruso with a friend working at a farmer's market. Photo credit: Kim Stoner, Connecticut Agricultural Experiment Station.

Ben Caruso harvesting beans

Ben Caruso harvesting beans. Photo credit: Kim Stoner, Connecticut Agricultural Experiment Station

New Leaf Farm, Dave and Christine Colson, Durham, ME

The Colsons grow vegetables on only 1/4 to 1/3 of their 9.5 acres of cultivated land in any given year. The rest of the land is in a cover crop rotation, which is central to their strategy of building soil and managing weeds. The small area producing vegetable crops is intensively managed to produce high quality, high value crops, particularly salad greens, through a long season, from May to Thanksgiving. They market their produce locally to restaurants, natural food stores, and a CSA, and see their close relationship to their customers and community as critical to their success. They are also deeply committed to education about organic agriculture at all levels, including their local Waldorf school, their apprentices, the Maine Organic Farming and Gardening Association, and farmers throughout the Northeast. Focal crops: Brassica greens for salad mix, tomatoes, butternut squash.  New Leaf Farm Case Study by the NEON Project.

Farmers Dave and Christine Colson

Farmers Dave and Christine Colson. Photo credit: Kim Stoner, Connecticut Agricultural Experiment Station

New Leaf Farm with row cover in foreground and a cover crop trial in background

New Leaf Farm with row cover in foreground and a cover crop trial in background. Photo credit: Kim Stoner, Connecticut Agricultural Experiment Station

Further Reading

 

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

eOrganic 3182

Organic Farm System: Biodesign Farm

lun, 2016/09/12 - 14:23

eOrganic authors:

Helen Atthowe, Biodesign Farm

Alex Stone, Oregon State University

Biodesign farmOrganic Farm System: Biodesign Farm
  • System Overview
  • Soil Management System
  • Insect Pest Management System
  • Disease Management System
System Overview About Biodesign Farm

Farmer: Helen Atthowe

Location: Stevensville, in western Montana (Fig. 1: Area Map)

Crops: Mixed vegetables. Main crops are tomatoes, bell peppers, eggplant, broccoli, cabbage, Brussels sprouts, and winter squash.

Markets: Regional farmers markets (75%) and wholesale to organic supermarkets and restaurants (25%)

Years in organic management: Biodesign began in 1993 and was certified organic with the Montana Department of Agriculture Organic Certification Program until 2008, when the farm joined with other small, local organic producers to form the Western Montana Sustainable Grower's Union. The farm was sold in 2010.

Total farm acreage: 30 acres

Cropped acreage: 8 acres

Landscape design: Two fields—one 6 acres and the other 2 acres. Fields were surrounded by native grassland–sagebrush steppe habitat, several pasture-based cattle operations, and some large-scale potato and small grain producers (Fig. 2: Farm Fields Map). "Old field" (2 acres) was cultivated from 1994 through 2005. In 2006, production moved to "New field" (6 acres).

Regional agricultural production: Ravalli County's 2012 gross agricultural production was $34,725,000, with 70% from livestock production and 30% from crops, mostly grains.

Climate and soils: Semiarid (13 to 16 inches of annual precipitation) with a frost-free growing season of 100 to 115 days. Average last frost is 30 May, and average first frost is 10 September. Spring is the wettest period of the year, with about 25% of annual precipitation falling in May and June. Summer temperatures reach the high 90s, and winter lows are regularly below zero. Soils are classified as capability class VI by the USDA Natural Resources Conservation Service and rated as "poor" for agricultural use (Fig. 2: Farm Fields Map).

Awards: Alternative Energy Resource Organization Sustainable Farm Award, 2000

Farm Philosophy

Rather than treating specific crops, problems, or pests, Biodesign focused on supporting natural nutrient and biological control cycles and on managing ecological relationships.

Key Farm Design and Soil and Habitat Building Strategies
  • Small crop fields embedded in native grass/pasture forest habitat
  • Reduced tillage
  • Perennial and annual living mulch to keep soil covered year-round and to provide winter shelter and interspersed season-long bloom for natural enemies
  • Selective mowing of the living mulch to provide
    • Regular addition of organic residues to the soil/soil microbial community
    • Shade and cooling for crops and beneficial enemies during hot, dry spells. During cool, wet periods, the living mulch was mowed short to enhance drying and increase ambient air temperatures. Following planting, it was left unmowed to provide a windbreak for seedlings and transplants.
  • Compost addition in the early years
  • Gravity-flow irrigation management:
    • Drip irrigation to avoid fruit and foliage wetting (for disease management)
    • Sprinkler irrigation to suppress specific pests such as flea beetles
Soil Management System: Build Soil to Support Natural Nutrient Cycles and Grow High-Yielding, High-Quality, Flavorful Crops

Biodesign's goals were to optimize soil organic matter, reduce tillage, support a diverse soil microbial community, and provide year-round soil cover for natural enemies. The soil management system (Soil Table 1) included:

  • Reduced tillage
  • Perennial and annual living mulches to provide year-round soil cover, with above- and below-ground plant diversity
  • Regular addition of mowed clover/weed soil amendments
  • Annual compost addition most years (1993–2002 on Old field and 2006–2007 on New field)
  • Alfalfa meal addition to crop rows in years when no compost was applied (Disease Table 2 and Table 3).
  • In Old field, soil organic matter (SOM) content climbed from 3.5% in 1993 to 5.7% in 2006, while cation exchange capacity (CEC) increased from 10.2 to 16.8 meq/100g (Soil Fig. 1).
  • In New field, SOM increased from 3.3% in 1993 (when New field was in permanent grass pasture) to an average of  5.2% in 2010 (after New field was cultivated for vegetable production, beginning in 2006). CEC increased from 9.8 to 11.7 meq/100g as SOM increased (Soil Fig. 2).
  • Macronutrients increased while the farm was in production. While some reached excessive levels during the 1990s, almost all eventually reached target levels.

The reduced tillage/living mulch system resulted in good yields of high-quality, flavorful crops and high levels of soil organic matter and soil nutrients. Soil health indicators generally showed positive trends (Soil Table 2).

Read more about the Biodesign soil management system here.

Insect Pest Management System: Maximize Ecological Function and Minimize Off-Farm Inputs

Biodesign's goal was to build and manage habitat for biological control organisms (e.g., insect predators and parasites, birds, bats, soil and foliar microorganisms) and to apply insecticides only when a pest was not sufficiently controlled by the system. Pests were sprayed only when absolutely necessary. The insect pest management system included both systemic practices (Insect Table 1) and pest-specific strategies (Insect Table 2):

  • Landscape-level diversity provided by small crop fields bordered on four sides by native grassland/pasture
  • Reduced tillage
  • Perennial and annual living mulch groundcover in row middles to provide in-field interspersed plant diversity; season-long pollen, nectar, and seed food sources; and winter cover
  • Selective mowing of the perennial living mulch to avoid disturbance of natural enemies at key pest pressure times
  • Irrigation management to discourage certain pests
  • Organic soil amendments to maintain balanced crop growth, thus suppressing insect pests
  • Three-year crop rotation by crop family (Solanaceae, Brassicaceae, Fabaceae)
  • Pesticides were applied only when necessary (Insect Table 2)  and applications ceased in 2000; up to 10% pest damage was tolerated in some crops to maintain a food source for natural enemies.

Crop yield and quality losses to insects decreased from 1993 through 2010, according to Helen. This observation is supported by reduced insecticide use (Insect Fig. 1), crop monitoring records (1993–2010), and on-farm research (2006). Farm records document good yields, less than 3% average crop damage across all crops (Insect Fig. 2 and Insect Fig. 5), and high predator/parasite populations (Insect Fig. 3 and Insect Fig. 4). Aphids on peppers and cabbageworms on brassicas were the main insect pests at Biodesign.

Read more about the Biodesign insect pest management system here.

Disease Management System: Create Conditions Unfavorable for Pathogen Growth

Biodesign's goal was to prevent disease incidence by managing for balanced crop growth and healthy soil, while utilizing good cultural practices such as rotation and irrigation management. The disease management system included both systemic practices (Disease Table 1) and disease-specific strategies (Disease Table 4):

  • Organic soil amendments to maintain balanced crop growth
  • Selective mowing of the between-row living mulch to maximize air flow and leaf and fruit drying
  • Drip irrigation and management to avoid foliar and fruit wetting
  • Three-year crop rotation by crop family (Solanaceae, Brassicaceae, Fabaceae).

Diseases, primarily bacterial speck of tomato (Pseudomonas syringae pv. tomato) and cucumber mosaic virus of pepper (Bromoviridae:Cucumovirus) were never highly damaging due in part to the dry climate. However, losses did occur. Over time, losses declined, especially those caused by bacterial speck as documented by crop quality monitoring records (1993–2010), possibly due to Biodesign Farm's design and soil- and habitat-building practices. Cucumber mosaic virus was observed at low levels on peppers in the early 2000s, but did not become more severe over time or affect crop yield.

Read more about the Biodesign disease management system here.

This article is part of the Biodesign Farm Organic Systems Description.

Table of Contents:

  • System Overview, Map 1, Map 2
  • Soil Management System, Soil Tables, Soil Figures
  • Insect Pest Management System, Insect Tables, Insect Figures
  • Disease Management System, Disease Tables

 

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

eOrganic 15582

CalCORE Research: Improving Biological Control of Lygus Bug and Cabbage Aphid

jeu, 2016/08/25 - 11:42

Video Transcript:

Carol Shennan: We try and address issues of pests and diseases and nutrients all in the same rotation systems, and that’s really what CalCORE—the core of CalCORE—is. And then we are also interested in the biological control of important pests, and most of that work focuses on either strawberry pests or pests of broccoli.

Chapter 1.1: Lygus Bug in Strawberry

Diego Nieto: Lygus bug is one of the two sort of key pests of strawberry in this region. If you look at the organic acreage in Santa Cruz County, it is worth about $23 million for strawberry. A conservative, very conservative, estimate for losses with respect to lygus damage is about 5%. That means annually there is over a million dollars of yield that is lost due to this particular pest just in organic strawberries in this county.

Tim Campion: The lygus bug feeds on the flower, and you can't visually see that the flower has been damaged until it starts developing into fruit and it will result in a fruit that they call cat-faced. It is kind of gnarled and unmarketable.

Jaime Lopez: The way we control our lygus bug and from the Extension’s outreach, is the best management practice right now is using vacuums, aspirators, that will come into the field and suck up the bugs and just grind them to pieces.

Chapter 1.2: Alfalfa Trap Crop: A Prevention, Scouting, & Management Tool

Diego Nieto: So lygus bug is a generalist feeding pest, which is to say that it doesn’t become problematic in strawberry because it loves strawberry, but rather because it is sort of available when the hillsides and all of the native plants have become dry as spring turns to summer. If we can utilize that polyphagous feeding behavior and take advantage of it by providing a plant host that is in fact preferred, then you can prevent pest establishment in a strawberry field. And of course with organic agriculture, prevention is steps 1, 2, and 3 in a good pest management program. So what we have done is implement alfalfa trap crops to attract lygus bugs.

In addition to the preventative component, alfalfa trap-cropping also provides a very efficient and effective means of scouting and management. So rather than scouting a very large strawberry field, with alfalfa trap crops you know exactly where to look. With respect to management, again there is lots of efficiency built into the system. The lygus bug pest pressure tends to be concentrated in this little three-row universe, which is one alfalfa trap crop and then the immediately adjacent strawberry row on either side. So these tractor-mounted vacuums can go through the three-row area and get the majority of lygus bugs and you can in that way conserve the beneficial insects, the predators, and the parasitoids that are in those strawberries.

Chapter 1.3: Identifying Lygus Bug Predators

Diego Nieto: Part of the aim here was to distinguish, identify, and characterize how predators operated in this trap crop system. So we were able to collect predators in commercial strawberry and look at their gut contents to see which ones had actually consumed lygus bug. We were able to identify 14 different predator groups that we found evidence of lygus predation. This included 8 different types of spiders, 3 true bugs, and 2 beetles. So there is a very big predator community that is in strawberry that is consuming lygus bug.

Chapter 1.4: Increased Predation Rates in Alfalfa Trap Crops

Diego Nieto: We were able to collect a significant amount of evidence that predation increases with increased prey abundance in alfalfa relative to strawberry.

Ultimately, when you look at yield in strawberry that are adjacent or associated with alfalfa trap crops compared to strawberry by themselves, what's exciting is you do get a yield improvement. So there is definitely an economic benefit to alfalfa trap crops.

Chapter 2.1: Cabbage Aphid in Brassicas: Improving Knowledge of the Beneficial Syrphid Community

Steve Pedersen: As far as brassicas are concerned, the cabbage aphid is by far the number one problem.

Diego Nieto: If you unofficially survey growers who deal with this pest on a routine basis, it sounds like there is about 15% yield loss in the form of contamination where these aphids get into the florets or the heads of a particular brassica.

More often than not the syrphid community will come in in a timely fashion and will effectively manage these cabbage aphid communities. But there is inconsistency and unpredictability with how these syrphids move in in terms of the quantity or the timeliness of their establishment. So the timing of when syrphids come in and establish in a field ends up being incredibly important and influential to the ultimate yield outcome of a particular organic brassica crop.

Some of our goals with respect to cabbage aphid and the syrphid community that is found in cole crops on the Central Coast involves distinguishing and characterizing the species in that syrphid community, determining how they interact with the timing of a broccoli growing season, particular aphid densities, how they complement possibly one another with those dynamics, and then to try and illustrate, communicate how those species operate—making sure people understand the differences between one species versus another and especially those species versus caterpillars so that no one is confusing a beneficial insect with a pest.

I think the management implications might be tailoring beneficial insectary habitats that have the most utility for these particular species. Some of these species they vary from smaller flies to larger flies and correspondingly from smaller larvae to larger larvae and so it is important to figure out which flowers—the flower types, the flower shapes, how accessible the nectar and pollen is—how that corresponds to particular syrphid species to make sure that we are getting the full benefit out of these insectary habitats.

Steve Pedersen: Identifying the roles of specific predators in organic systems is very exciting and that’s a really neat component of the CalCORE project.

 

 

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

eOrganic 15425

Targeted Sheep Grazing in Organic Dryland Systems

mar, 2016/08/23 - 16:51

Join eOrganic for a webinar on targeted sheep grazing in organic dryland systems, presented by Fabian Menalled, Patrick Hatfield and Perry Miller of Montana State University in Bozeman, MT. The webinar is free and open to the public, and advance registration is required. 

Register now at https://attendee.gotowebinar.com/register/7793261828690587906

About the Webinar

Organic production has become a major agricultural, economic, and cultural force, but heavy reliance on tillage hinders the long-term sustainability of such systems, particularly in a dryland environment. This limitation has prompted interest in developing reduced tillage practices that can be used successfully on organic farms. One approach is to develop integrated crop-livestock production systems that seek to replace tillage with targeted grazing to manage weeds and terminate cover crops. The presenters combined experimental plot studies with on-farm research to increase their knowledge on the environmental, management, and economic challenges facing integrated crop-sheep organic systems in Montana.

In this webinar, they will summarize their experience regarding agronomic and economic performance, weed management challenges, and animal husbandry of integrated crop-sheep organic system. While successful in reducing tillage intensity, perennial weed pressure continues to challenge the ability of organic farmers to adopt these systems. They will discuss alternative approaches to foster a successful adoption of conservation-tillage practices by organic farmers in dryland environments.  

System Requirements

View detailed system requirements here. Please connect to the webinar 10 minutes in advance, as the webinar program will require you to download software. To test your connection in advance, go here. You can either listen via your computer speakers or call in by phone (toll call). Java needs to be installed and working on your computer to join the webinar.  If you are running Mac OSU with Safari, please test your Java at http://java.com/en/download/testjava.jspprior to joining the webinar, and if it isn't working, try Firefox or Chrome.

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

eOrganic 20198

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