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Making and Using Compost for Organic Farming

Fri, 05/31/2019 - 16:47

eOrganic authors:

Emily Marriott, University of Illinois at Urbana-Champaign

Ed Zaborski, University of Illinois at Urbana-Champaign

Introduction

Composting transforms raw organic residues into humus-like material through the activity of soil microorganisms. Mature compost stores well and is biologically stable, free of unpleasant odors, and easier to handle and less bulky than raw organic wastes. In agronomic and horticultural operations, compost can be used as a soil amendment, seed starter, mulch, container mix ingredient, or natural fertilizer, depending on its characteristics. Composting can also reduce or eliminate weed seeds and plant pathogens in organic residues.

Compost provides many benefits as a soil amendment and a source of organic matter by improving soil biological, chemical, and physical characteristics:

  • Increases microbial activity
  • Enhances plant disease suppression
  • Increases soil fertility
  • Increases cation exchange capacity
  • Improves soil structure in clayey soils
  • Improves water retention in sandy soils
  • Reduces bioavailability of heavy metals
Overview of the Composting Process

Microorganisms drive the composting process, so creating an optimal environment for microbial activity is crucial for successful and efficient composting. Assembling an appropriate mix of organic residues or feedstocks and maintaining adequate moisture and oxygen levels are all necessary.

As soon as feedstocks are compiled, the composting process begins. As microorganisms begin to decompose the organic materials, the compost pile heats up and the active phase of composting begins. During this phase of rapid decomposition, temperatures in the pile increase to 130–150°F and may remain elevated for several weeks. Maintaining adequate aeration during this phase of intense microbial activity is especially important because aerobic decomposition is most efficient and produces finished compost in the shortest amount of time. As readily available organic matter is consumed and decomposition slows, temperatures in the compost pile decrease to around 100°F and the curing phase begins. At this stage, the compost can be stockpiled.

Common methods of on-farm composting include static piles, windrows (elongated piles), and in-vessel (enclosed) composting. Static piles are compost piles that are not turned. To meet National Organic Program requirements, static pile systems must be aerated to sustain microbial activity and adequate temperatures. To that end, perforated pipe is installed at the base of the pile and in some cases fans or blowers are used to force air through the pile.

Static compost piles with passive aeration tubes
Figure 1. Static compost piles with passive aeration tubes. Photo credit: Robert Rynk, Compost Education and Resources for Western Agriculture project, Washington State University.

Windrows, or enlongated piles of compost feedstocks, are turned or mixed regularly to aerate the pile and to reestablish pore space.

Profiles of compost windrows at a dairy in eastern Washington
Figure 2. Profiles of compost windrows at a dairy in eastern Washington. Photo credit: David Granatstein, Compost Education and Resources for Western Agriculture project, Washington State University.

this farm-scale rotating drum is used at a Texas site
Figure 3. An example of in-vessel composting. This farm-scale rotating drum is used at a Texas site. Photo credit: Robert Rynk, Compost Education and Resources for Western Agriculture project, Washington State University.

How to Compost

Several comprehensive resources providing detailed explanations of the composting process and specific information on how to make compost are available; examples include The Art and Science of Composting (Cooperband, 2002a), Composting on Organic Farms (Baldwin and Greenfield, 2009), and On-Farm Composting Handbook (Rynk, 1992).

Large-scale composting is regulated in most states. Check with your state government to ensure compliance with composting regulations.

Compost and the National Organic Program

The use of composted plant and animal materials to maintain or improve soil organic matter is supported by the National Organic Program (NOP) final rule (United States Department of Agriculture [USDA], 2000):

The producer must manage plant and animal materials to maintain or improve soil organic matter content in a manner that does not contribute to contamination of crops, soil, or water by plant nutrients, pathogenic organisms, heavy metals, or residues of prohibited substances.

~ 7 CFR 205.203(c)

The composition, production, and use of compost in organic production systems is regulated by the NOP final rule; the NOP provided clarification of these regulations in guidance on the allowance of green waste in organic production systems (NOP, 2010a) and in draft guidance on compost and vermicompost in organic crop production (NOP, 2010b). In addition, the NOP provided guidance on uncomposted, processed animal manures in organic crop production (NOP, 2010c).

Composition

According to NOP's guidance on the allowance of green waste in organic production systems (NOP, 2010a) and draft guidance on compost and vermicompost in organic crop production (NOP, 2010b), approved feedstocks for compost include:

  • Plant and animal materials, such as, crop residues, animal manure, food waste, yard waste
  • Nonsynthetic substances not prohibited by 7 CFR 205.602
  • Synthetic substances specifically allowed for use as a compost feedstock per 7 CFR 205.601 [only "newspapers or other recycled paper, without glossy or colored inks"]
  • Synthetics approved for use as plant or soil amendments

NOP regulation states that compost that is produced with prohibited feedstocks (urea, recycled wallboard, or sewage sludge, for example) is prohibited, and it does not permit the use of compost that contains synthetic substances that are not on the National List of synthetic substances allowed for use in organic crop production (see Can I Use this Input on My Organic Farm?). However, recognizing that background levels of pesticides are present in the environment (referred to as unavoidable residual environmental contamination—UREC—in the regulations) and may be present in organic production systems, NOP regulation does not mandate zero tolerance for synthetic pesticide residues in inputs, such as compost. According to NOP guidance,

Green waste and green waste compost that is produced from approved feedstocks, such as, non-organic crop residues or lawn clippings may contain pesticide residues. Provided that the green waste and green waste compost (i) is not subject to any direct application or use of prohibited substances (i.e. synthetic pesticides) during the composting process, and (ii) that any residual pesticide levels do not contribute to the contamination of crops, soil or water, the compost is acceptable for use in organic production.

~ NOP, 2010a

What constitutes "contamination of crops, soil or water"? The NOP final rule states (USDA, 2000, 7 CFR 205.671) "When residue testing detects prohibited substances at levels that are greater than 5 percent of the Environmental Protection Agency's tolerance for the specific residue detected or unavoidable residual environmental contamination, the agricultural product must not be sold, labeled, or represented as organically produced." NOP is thus far silent on what constitutes contamination of soil or water.

Compost feedstocks may contain synthetic pesticide contaminants that are not degraded in the composting process, and can contribute to crop, soil, or water contamination. This was the case for the herbicide clopyralid, which was used on turfgrass as well as in agriculture. It passes through animals in the urine, and therefore if they eat forage with clopyralid residues, the herbicide ends up in the bedding and potentially in the compost. Similarly, clopyralid can contaminate compost made from clippings from treated lawns. The uses of this herbicide have been restricted to avoid this problem, but it is advisable to ask the compost vendor or the provider of raw feedstock materials about such potential contaminants. For more information, see the Washington State University Puyallup Research Center publications on clopyralid in compost.

The source of all compost feedstock materials should be known to ensure that they are allowed for use in organic production. Knowing the feeding practices used for manure sources and having the manure tested can also provide information about possible antibiotic and heavy metal contamination. The use of compost containing these contaminants is not permitted in organic crop production; however, the organic rule does not require that manures come from organic livestock farms to be used in organic compost production.

The use of broiler litter as a feedstock for compost production poses some additional concerns. Arsenic is a component of some feed medications or growth promoters used in commercial broiler operations. The majority of arsenic consumed by poultry is excreted and incorporated into the litter, leading to the potential for build-up in the soil and leaching from compost piles into lakes and streams. For more information, consult the ATTRA publication, Arsenic in Poultry Litter: Organic Regulations, by Bellows (2005).

Increasing use of copper in broiler and hog operations may result in manures with high concentrations of copper. Copper foot baths are also common in cattle production. While copper is a necessary plant nutrient, it can become toxic in very high concentrations. Sustained use of compost from these sources could contribute to copper build-up in the soil in the long-term, especially in operations that rely on copper as a pesticide.

Production

The NOP regulations refer to production methods for compost in the context of managing plant and animal materials to maintain and improve soil organic matter content:

The producer must manage plant and animal materials to maintain or improve soil organic matter content in a manner that does not contribute to contamination of crops, soil, or water by plant nutrients, pathogenic organisms, heavy metals, or residues of prohibited substances. Animal and plant materials include:
…
   (2) Composted plant and animal materials produced though a process that:
      (i) Established an initial C:N ratio of between 25:1 and 40:1; and
      (ii) Maintained a temperature of between 131°F and 170°F for 3 days using an in-vessel or static aerated pile system; or
      (iii) Maintained a temperature of between 131°F and 170°F for 15 days using a windrow composting system, during which period, the materials must be turned a minimum of five times.

~ 7 CFR 205.203(c)(2), USDA, 2000

The NOP's draft guidance on compost and vermicompost in organic crop production (NOP, 2010b) identifies these processes as examples of methods for producing acceptable composts, and states that:

An example of another acceptable composting method is when:
   a. Compost is made from allowed feedstock materials (either nonsynthetic substances not
prohibited at §205.602, or synthetics approved for use as plant or soil amendments), and
   b. The compost pile is mixed or managed to ensure that all of the feedstock heats to the minimum of 131°F (55°C) for a minimum of three days. The monitoring of the above parameters must be documented in the Organic System Plan in accordance with §205.203(c) and submitted by the producer and verified during the site visit.

~ NOP, 2010b

NOP compost requirements can also be met by vermicompost (compost produced by the action of earthworms), so long as:

a. It is made from allowed feedstock materials (either nonsynthetic substances not prohibited at §205.602, or synthetics approved for use as plant or soil amendments);
b. Aerobicity is maintained by regular additions of thin layers of organic matter at 1–3 day intervals;
c. Moisture is maintained at 70–90%; and
d. The duration of vermicomposting is at 6–12 months for outdoor windrows, 2–4 months for indoor container systems, 2–4 months for angled wedge systems, or 30–60 days for continuous flow reactors.

~ NOP, 2010b

Compost production practices, including the type and source of all feedstock materials, temperature monitoring logs by date, and practices used to achieve uniform elevated temperatures, should be described in the organic system plan (OSP).

Use

Compost made in accordance with the above production criteria may be applied in organic production systems without restriction on the time interval between application and crop harvest.

Composts that don't meet the above production criteria may still be used in organic farming. However, if they contain animal manure, they must be applied to agricultural land in accordance with NOP regulations for manure, which state that raw animal manure must be composted unless at least one of the following conditions is satisfied:

  • Applied to land used for a crop not intended for human consumption
  • Incorporated into the soil not less than 120 days prior to the harvest of a product whose edible portion has direct contact with the soil surface or soil particles
  • Incorporated into the soil not less than 90 days prior to the harvest of a product whose edible portion does not have direct contact with the soil surface or soil particles

~ 7 CFR 205.203(c)(1), USDA, 2000

Compost Quality

Compost quality varies depending on the raw organic materials (feedstocks), the composting process used, and the state of biological activity. Before using compost as a soil amendment, it is a good idea to evaluate its quality by determining moisture content, organic matter content, C:N ratio, and pH (Table 1).

Table 1. Qualities of compost for on-farm use and how to test (after Cooperband, 2002a). Quality Optimum How to test Source of organic matter Should have a good organic matter content (40-60%) Have organic matter tested by a soil lab Source of nitrogen 10–15:1 C:N ratio Have C:N ratio tested by a soil lab Neutral pH 6–8 Use soil pH kit at home or have pH tested by a soil lab Low soluble salts If compost will be spread in the fall, no test necessary N/A If compost will be spread before planting, levels should be below 10 dS Have soluble salts tested by a soil lab No phytotoxic compounds Good seed germination (>85%) Plant 10 seeds in a small pot Weed-free No or few weed seeds Moisten compost and watch for weed seedling growth Compost and Disease Suppression

Compost can be effective at controlling some soil-borne diseases, particularly root-rot diseases. By providing a favorable environment and food source, compost encourages the growth of microorganisms that compete with, parasitize, or produce natural antibiotics against plant pathogens. Additionally, increased plant vigor due to compost application can increase resistance to plant pathogens. For more information see the chapter on Compost and Disease Suppression in the ATTRA publication Sustainable Management of Soil-Borne Plant Diseases by Sullivan (2004). See a related article to learn how composting can reduce or eliminate weed seeds and plant pathogens in crop residues and other organic feedstocks.

Compost and Soil Fertility

Generally, compost can be considered more as a soil conditioner than as a fertilizer substitute because it improves plant productivity primarily by improving physical and biological soil properties and increasing soil organic matter, rather than by directly supplying significant amounts of plant-available nutrients. By increasing soil organic matter content, which fuels microbial activity and nutrient cycling, compost applications will increase overall soil fertility. Over subsequent growing seasons, the nitrogen applied in compost will become plant-available.

Compost Application Rates

Compost should be considered a slow-release source of nitrogen. Most nitrogen remaining after completion of the composting process is bound into organic forms and thus not available immediately for plant uptake. Compost routinely applied at rates high enough to meet immediate crop N requirements will almost always result in excess P and K application. Excess P can result in surface water pollution (and potentially threaten organic certification). In some cases, excess K can upset crop nutrition balance.

Compost application rates can be calculated using fertilizer recommendations from soil tests, compost nutrient analysis, and methods similar to those used to determine manure application rates. When using this method, nutrient availability in compost must also be taken into account. General guidelines suggest that 10 to 25% of compost N will be plant-available during the first year of application. Estimates for P and K availability in the first year are higher, 40% and 60% respectively. It is important to keep in mind that these are only estimates and actual availability will depend on the nature of the compost and—for N especially—conditions during the growing season that affect N mineralization. Composting on the Organic Farm, by Baldwin and Greenfield (2009), provides detailed instructions for calculating application rates.

This vegetable producer in Washington State built his own compost spreader from existing equipment.
Figure 4. This vegetable producer in Washington State built his own compost spreader from existing equipment. Photo credit: David Granatstein, Compost Education and Resources for Western Agriculture project, Washington State University.

References and Citations 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 2880

Legume Inoculation for Organic Farming Systems

Fri, 05/31/2019 - 16:25

eOrganic author:

Dr. Julie Grossman, North Carolina State University

What Is Inoculation?

Legumes growing together with soil bacteria called rhizobia work together to take atmospheric nitrogen (N2) found in soil air spaces and transform—or fix—it into a plant-available form through the process called Biological Nitrogen Fixation (BNF) (Fig. 1). Even though the atmosphere is almost 80% N, the N2 gas is such that plants can't use it for their own growth and development unless it is fixed. However, neither legumes nor the rhizobia can do the job alone. The process must occur as part of a mutually beneficial—or symbiotic—relationship with soil-dwelling rhizobia bacteria. Rhizobia form root nodules on the host legume, thereby providing the plant with transformed N in exchange for a portion of the carbohydrates made by the plant.

Figure 1. Biological Nitrogen Fixation provides nitrogen fertility in legume-based cropping systems.
Figure 1. Biological Nitrogen Fixation provides nitrogen fertility in legume-based cropping systems. Figure credit: Nape Mothapo, North Carolina State University.

In order for BNF to occur, certain things need to happen. First, because there are many types of rhizobia, the right type of rhizobia to form nodules with your particular legume must be in contact with the growing legume root. Additionally, the rhizobia must be efficient in fixing atmospheric N, and, of course, they must be alive! The application of the recommended type of bacteria to the seed or soil prior to planting is called inoculation. With so much to take into account to produce a strong healthy legume–rhizobia relationship, successful inoculation can seem daunting. This document will introduce you to legume inoculation and recommend proper inoculation methods for certified organic growers. Readers can view related articles for additional information on general soil fertility in organic farming systems and soil microbial nitrogen cycling in organic farming systems.

Two ways to help provide your grain, forage, or cover crop legume with the N it needs for growth and development are: (1) make sure your legumes are well nodulated, and (2) verify that nodules contain effective rhizobia. The presence of nodules alone does not ensure that N is being actively fixed. Some rhizobia are ineffective, meaning that they can form nodules, but do not fix nitrogen. To check for effective rhizobia and nitrogen fixation in the field, dig out several plants and wash root systems in water to remove soil. Then select 2–3 nodules from each plant and slice them in half. Nodules that have pink or red interiors indicate that the rhizobia are hard at work fixing nitrogen, while greenish or white interiors contain ineffective rhizobia. Inoculation of your seeds prior to planting is one proven way to have the correct type of bacteria present within the vicinity of the legume's growing root.

When is it Necessary to Inoculate? Species specificity and cross inoculation groups

Figure 2. Well-formed nodules on the root system of a vetch plant.
Figure 2. Well-formed nodules on the root system of a vetch plant. Photo credit: Julie Grossman, North Carolina State University.

Rhizobia bacteria are picky little critters and are fairly specific about which legume species they will select as a host to form nodules. It is important that you purchase the correct type of bacteria for your legume seed. Some species of rhizobia can infect more than one species of legume. For example, peas and vetch all form nodules with the rhizobia species Rhizobium leguminosarum, while true clovers are all infected by R. trifolii. The groups of legumes infected by the same rhizobia are called cross-inoculation groups (Table 1.). Sometimes the correct type of bacteria that can form nodules with the legume you are planting is already present in the field. In order to ensure that the correct type of bacteria is ready and waiting for your germinating seed in the soil, farmers commonly practice inoculation with specific groups of bacteria recommended for your legume type.

Table 1. Cross-inoculation groups of legumes and rhizobia. Legume group Manufacturers inoculation group code Rhizobia species Alfalfa and sweetclover

A

Rhizobium meliloti True clovers B R. trifolii Peas and vetch (true) C R. leguminosarum Soybean S Bradyrhizobium japonicum Birdsfoot trefoil K R. loti Crownvetch M Rhizobium spp. Is Inoculation of My Legumes a Requirement for Good Growth?

Inoculation is recommended when the field has no past history of growth of your particular legume, or when you have a high value crop for which you want to ensure successful growth. Often, inoculant rhizobia can remain viable in the soil without the presence of a legume for years, and then be ready to form nodules when its host plant is sown. Field history that includes a legume can increase the soil rhizobia population and result in improved nodulation (Mothapo et al., 2011). Specifically, inoculation is recommended if the field has been out of host plant production for 3–5 years, or never planted to the host. Further, inoculation can help increase rhizobia populations in fields with unfavorable environmental conditions for the bacteria's long-term survival, such as pH below 6.0, extremely sandy soils, or periodically-flooded conditions. Past history that includes a diversity of legume species—common in organic systems—has been shown to increase the diversity of rhizobia types present in the field (Grossman et al., 2011).

How Do I Inoculate My Legumes?

Take care of your inoculants—they are alive!

Inoculants come in many forms, but the most common is as a bacteria-infused peat that has a black, dust-like appearance. The bacteria on the peat particles may not look like much, but they are indeed alive, and should be treated with care. Although peat has been shown to mediate unfavorable conditions such as high temperatures and long storage times, certain precautions are necessary in order to increase inoculant effectiveness.

Inoculant packages come with an expiration date that should be heeded—use of an inoculant past its expiration date could mean that you are adding bacteria to your seed that are not alive or healthy. Treat the inoculant as you might treat a living organism—don’t leave it in the sun for extended periods of time, and store it in a cool dry place when not in use, such as a refrigerator. Many manufacturer recommendations offer a suggested temperature of 40°F.

Inoculants can be added to the soil or directly to your seed prior to planting.

In direct-soil application, granular inoculants can be added to the soil via the fertilizer box of a standard planter or drill, as long as the box has no history of substances prohibited in organic production, or the box is thoroughly cleaned prior to use. Flow of the inoculant should be calibrated in order to ensure a steady flow of material to the field. Frozen concentrated and liquid inoculant cultures are also available. In this case, the frozen cultures should be thawed and diluted according to manufacturers' directions and added to a water tank for field application in the seed row. Field application of inoculants requires more volume of inoculant to be added than seed-applied, in order to ensure the inoculant comes in contact with your legume seed.

In seed-applied inoculant, a more common practice among small-scale organic producers, the bacteria is mixed with the seed prior to planting. Seed should not be mixed in a small space such as a planter box, but instead on a large surface where all of the seeds have the opportunity to come into contact with the inoculant. Suggested places for mixing your seed include the bed of your pickup truck, a tarp on the ground, or in a tub.

Stickers—adhesives that can be used to ensure that the peat inoculant adheres to your seed—are commonly used to ensure good contact between the seed and bacteria. Research has shown increase in nodulation when stickers are used. Stickers can be commercially purchased or made at home using dilutions of milk or molasses (1 part sticker to 10 parts water is common). To use a sticker, mix seeds with just enough sticker to moisten the seeds, then add the inoculant to the moistened seeds. Be careful not to add too much liquid or the moisture could cause premature germination of your seeds. Air dry your seeds in the shade, then plant within 24 hours. Air drying the seeds will keep the moist seeds and inoculum from adhering to and plugging up your planter. If planting is not possible immediately after inoculation, inoculate again. Some seed comes pre-inoculated with a sticker. This type of inoculant should be treated with the same precautions as other types.

How Much Inoculant Should I Use?

The amount of inoculant to add to your seeds or field often depends on the length of time that has elapsed since the field was last inoculated. For new plantings, follow the inoculant manufacturer's directions on the package. Some farmers have found that after an initial inoculation event no inoculation is necessary in future years for good nodulation to occur. No general recommendation can be provided regarding survival of rhizobia in a field after a single inoculation event, as survial depends on individual field conditions such as soil type, pH, soil moisture, and rhizobia type.

What are the Precautions for Organic Farming Systems?

Growers should be aware of specific issues when using purchased inoculants in organic production of grains, cover-, and forage crops. Of interest to certified organic growers is the prohibition on the use of genetically modified organisms, ionizing radiation, or sewage sludge in the production of the inoculants. Some inoculants are produced using recombinant DNA technology—such inoculants cannot be used in organic production.  

The Organic Materials Review Institute (OMRI) is a non-profit organization that provides external review of products for use in organic systems. When the OMRI review panel approves both the active and non-active (inert) ingredients of a product for compliance, then the product becomes OMRI-listed and can display an "OMRI-approved" label. A critical part of organic certification is maintenence of inoculant supply company documentation that provides inoculant ingredients, or certifies OMRI approval. Many companies have issued such information as written responses that are available through the internet. Various OMRI-approved inoculants are produced by Becker Underwood, and INTEX microbials. A full list of OMRI-approved inoculants can be found on the OMRI website

IMPORTANT: Before using any input product in your organic farming system, make sure that the brand name product is listed in your Organic System Plan and approved by your USDA-approved certifier. Note that, although OMRI and WSDA lists are good places to identify potentially useful products, all products that you use MUST be approved by your USDA-accredited certifier. For more information on how to determine whether a product can be used on your farm, see Can I Use This Input on My Organic Farm?

References Cited
  • Grossman, J. M., M. E. Schipanski, T. Sooksanguan, and L. E. Drinkwater. 2011. Diversity of rhizobia nodulating soybean [Glycine max (Vinton)] varies under organic and conventional management. Applied Soil Ecology 50: 14–20. (Available online at: http://dx.doi.org/10.1016/j.apsoil.2011.08.003) (verified 20 April 2012).
  • Mothapo, N., J. Grossman, and J., Maul. 2011. Hairy vetch cultivation history affects nodulation and biological nitrogen fixation across host genotypes. ASA-CSSA-SSSA International Annual Meetings, Oct 16–19, 2011, San Antonio, TX. (Available online at: http://a-c-s.confex.com/crops/2011am/webprogram/Paper66799.html) (verified 20 April 2012).
Additional Resources
  • Beegle, D. 2001. Soil fertility management for forage crops establishment. Agronomy Facts 31-B. Penn State, College of Agricultural Sciences, Cooperative Extension. (Available online at: http://cropsoil.psu.edu/extension/facts/agronomy-facts-31b) (verified 20 April 2012).
  • Durst, D., and S. Bosworth. 1986. Inoculation of forage and grain legumes. Agronomy Facts 11. Penn State Department of Crop and Soil Sciences, Cooperative Extension. (Available online at: http://cropsoil.psu.edu/extension/facts/agronomy-facts-11) (verified 20 April 2012).
  • Park, S., C. Cao, and B. B. McSpadden Gardener. 2010. Inoculants and soil amendments for organic growers. Fact Sheet SAG-17-10. The Ohio State University Extension. (Available online at: http://ohioline.osu.edu/sag-fact/pdf/0017.pdf) (verified 21 May 2012).

 

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 4439

Brassicas and Mustards for Cover Cropping in Organic Farming

Fri, 05/31/2019 - 16:16

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.

Type: Annual (usually winter or spring; summer use possible)
Roles: Prevent erosion, suppress weeds and soilborne pests, alleviate soil compaction and scavenge nutrients
Mix with: Other brassicas or mustards, small grains or crimson clover
Species: Brassica napus, Brassica rapa, Brassica juncea, Brassica hirta, Raphanus sativus, Sinapsis alba

Nomenclature Note: The cover crops described in this article all belong to the family Brassicaceae. Most, but not all, of the species belong to the genus Brassica. In common usage, the various species are sometimes lumped together as "brassicas" and sometimes distinguished as "brassicas" vs. "mustards." In this article, we will use brassicas as an umbrella term for all species; mustards will be used to distinguish that subgroup, which has some unique characteristics.

Adaptation Note: This article addresses management of eight different cover crop species with varying degrees of winter hardiness. Some can be managed as winter or spring annuals. Others are best planted in late summer for cover crop use but will winter-kill. Consult the information on management, winter hardiness and winter vs. spring use and the examples throughout the chapter, then check with local experts for specific adaptation information for your brassica cover crop of choice.

Introduction

Brassica and mustard cover crops are known for their rapid fall growth, great biomass production, and nutrient scavenging ability. However, they are attracting renewed interest primarily because of their pest management characteristics. Most Brassica species release chemical compounds that may be toxic to soil borne pathogens and pests, such as nematodes, fungi and some weeds. The mustards usually have higher concentrations of these chemicals.

Brassicas are increasingly used as winter or rotational cover crops in vegetable and specialty crop production, such as potatoes and tree fruits. There is also growing interest in their use in row crop production, primarily for nutrient capture, nematode trapping, and biotoxic or biofumigation activity. Some brassicas have a large taproot that can break through plow pans better than the fibrous roots of cereal cover crops or the mustards. Those brassicas that winter-kill decompose very quickly and leave a seedbed that is mellow and easy to plant in.

With a number of different species to consider, you will likely find one or more that can fit your farming system. Don't expect brassicas to eliminate your pest problems, however. They are a good tool and an excellent rotation crop, but pest management results are inconsistent. More research is needed to further clarify the variables affecting the release and toxicity of the chemical compounds involved.

Mustard mix 'Caliente' cover crop in bloom
Figure 1. Mustard mix 'Caliente' in bloom at Kenagy Family Farm in Albany, OR. Photo credit: Alex Stone, Oregon State University.

Benefits Erosion control and nutrient scavenging

Brassicas can provide greater than 80% soil coverage when used as a winter cover crop (Haramoto and Gallandt, 2004). Depending on location, planting date and soil fertility, they produce up to 8,000 lb. biomass/A. Because of their fast fall growth, brassicas are well-suited to capture soil nitrogen (N) remaining after crop harvest. The amount of nitrogen captured is mainly related to biomass accumulation and the amount of N available in the soil profile.

Because they immobilize less nitrogen than some cereal cover crops, much of the N taken up can become available for uptake by main crops in early to late spring. Brassicas can root to depths of 6 feet or more, scavenging nutrients from below the rooting depth of most crops. To maximize biomass production and nutrient scavenging in the fall, brassicas must be planted earlier than winter cereal cover crops in most regions, making them more difficult to fit into grain production rotations.

Pest management

All brassicas have been shown to release biotoxic compounds or metabolic byproducts that exhibit broad activity against bacteria, fungi, insects, nematodes, and weeds. Brassica cover crops are often mowed and incorporated to maximize their natural fumigant potential. This is because the fumigant chemicals are produced only when individual plant cells are ruptured.

Pest suppression is believed to be the result of glucosinolate degradation into biologically active sulfur containing compounds call thiocyanates (Gardiner et al., 1999; Petersen et al., 2001). To maximize pest suppression, incorporation should occur during vulnerable life-stages of the pest (Williams and Weil, 2004).

The biotoxic activity of brassica and mustard cover crops is low compared to the activity of commercial fumigants (Smith et al., 2005). It varies depending on species, planting date, growth stage when killed, climate, and tillage system. Be sure to consult local expertise for best results.

The use of brassicas for pest management is in its infancy. Results are inconsistent from year to year and in different geographic regions. Different species and varieties contain different amounts of bioactive chemicals. Be sure to consult local expertise and begin with small test plots on your farm.

Disease management

In Washington, a SARE-funded study of brassica green manures in potato cropping systems compared winter rape (Brassica napus) and white mustard (Sinapis alba) to no green manure, with and without herbicides and fungicides. The winter rape system had a greater proportion of Rhizoctonia-free tubers (64%) than the white mustard (27%) and no green manure (28%) treatments in the non-fumigated plots. There was less Verticillium wilt incidence with winter rape incorporation (7%) than with white mustard (21%) or no green manure incorporation (22%) in non-fumigated plots (Collins et al., 2006).

In Maine, researchers have documented consistent reductions in Rhizoctonia (canker and black scurf) on potato following either rapeseed green manure or canola grown for grain (Larkin and Griffin, 2007; Larkin et al., 2006). They have also observed significant reductions in powdery scab (caused by Spongospora subterranea) and common scab (Streptomyces scabiei) following brassica green manures, especially an Indian mustard (B. juncea) green manure (Larkin and Griffin, 2007; Larkin et al., 2006).

Nematode management

In Washington state, a series of studies addressed the effect of various brassica and mustard cover crops on nematodes in potato systems (Matthiessen and Kirkegaard, 2006; Melakeberhan et al., 2006; Mojtahedi et al., 1991; Mojtahedi et al., 1993; Riga et al. 2003).  The Columbia root-knot nematode (Meloidogyne chitwoodi) is a major pest in the Pacific Northwest. It is usually treated with soil fumigants costing $20 million in Washington alone. Brassicas must be planted earlier than winter cereal cover crops in most regions.

Rapeseed, arugula and mustard were studied as alternatives to fumigation. The brassica cover crops are usually planted in late summer (August) or early fall and incorporated in spring before planting mustard.

Results are promising, with nematodes reduced up to 80%, but because of the very low damage threshold, green manures alone cannot be recommended for adequate control of Meloidogyne chitwoodi in potatoes. The current recommended alternative to fumigation is the use of rapeseed or mustard cover crop plus the application of MOCAP. This regimen costs about the same as fumigation (2006 prices).

Several brassicas are hosts for plant parasitic nematodes and can be used as trap crops followed by an application of a synthetic nematicide. Washington State University nematologist Ekaterini Riga has been planting arugula in the end of August and incorporating it in the end of October.

Nematicides are applied two weeks after incorporation, either at a reduced rate using Telone or the full rate of Mocap and Temik. Two years of field trials have shown that arugula in combination with synthetic nematicides reduced M. chitwoodi to economic thresholds.

Longer crop rotations that include mustards and non-host crops are also effective for nematode management. For example, a three-year rotation of potatoes>corn>wheat provides nearly complete control of the northern root-knot nematode (Meloidogyne hapla) compared to methyl bromide and other broad-spectrum nematicides.

However, because the rotation crops are less profitable than potatoes, they are less commonly used. Not until growers better appreciate the less tangible long-term cover crop benefits of soil improvement, nutrient management, and pest suppression will such practices be more widely adopted.

In Wyoming, oilseed radish (Raphanus sativus) and yellow mustard (Sinapsis alba) reduced the sugar beet cyst nematode populations by 19-75%, with greater suppression related to greater amount of cover crop biomass (Koch, 1995). In Maryland, rapeseed, forage radish, and a mustard blend did not significantly reduce incidence of soybean cyst nematode (which is closely related to the sugar beet cyst nematode). The same species, when grown with rye or clover, did reduce incidence of stubby root nematode (R. Weil, personal communication, 2007). Also in Maryland, in no-till corn on a sandy soil, winter-killed forage radish increased bacteria-eating nematodes, rye and rapeseed increased the proportion of fungal feeding nematodes, while nematode communities without cover crops were intermediate. The Enrichment Index, which indicates a greater abundance of opportunistic bacteria–eating nematodes, was 23% higher in soils that had brassica cover crops than the unweeded control plots. These samples, taken in November, June (a month after spring cover crop kill), and August (under no-till corn), suggest that the cover crops, living or dead, increased bacterial activity and may have enhanced nitrogen cycling through the food web (R. Weil, personal communication, 2007).

Weed management

Like most green manures, brassica cover crops suppress weeds in the fall with their rapid growth and canopy closure. In spring, brassica residues can inhibit small seeded annual weeds such as pigweed, shepherds purse, green foxtail, kochia, hairy nightshade, puncturevine, longspine sandbur, and barnyardgrass (Munoz and Graves), although pigweed was not inhibited by yellow mustard (Haramoto and Gallandt, 2005b).

In most cases, early season weed suppression obtained with brassica cover crops must be supplemented with cultivation to avoid crop yield losses from weed competition later in the season. As a component of integrated weed management, using brassica cover crops in vegetable rotations could improve weed control (Boydston and Al-Khatib, 2005).

In Maine, the density of 16 weed and crop species was reduced 23% to 34% following incorporation of brassica green manures, and weed establishment was delayed by two days, compared to a fallow treatment. However, other short-season green manure crops including oat, crimson clover, and buckwheat similarly affected establishment (Haramoto and Gallandt, 2004).

In Maryland and Pennsylvania, forage radish is planted in late August and dies with the first hard frost (usually December). The living cover crop and the decomposing residues suppress winter annual weeds until April and result in a mellow, weed-free seedbed into which corn can be no-tilled without any preplant herbicides. Preliminary data show summer suppression of horseweed but not lambsquarters, pigweed, or green foxtail (R. Weil, personal communication, 2007).

Mustard cover crops have been extremely effective at suppressing winter weeds in tillage-intensive, high-value vegetable production systems in Salinas, CA. Mustards work well in tillage-intensive systems because they are relatively easy to incorporate into the soil prior to planting vegetables. However, the growth and biomass production by mustards in the winter is not usually as reliable as that of other cover crops such as cereal rye and legume/cereal mixtures (Brennan and Smith, 2005).

Soil structure management

Some brassicas (forage radish, rapeseed, turnip) produce large taproots that can penetrate up to 6 feet to alleviate soil compaction (R. Weil, personal communication, 2007). This so-called "biodrilling" is most effective when the plants are growing at a time of year when the soil is moist and easier to penetrate. Their deep rooting also allows these crops to scavenge nutrients from deep in the soil profile. As the large tap roots decompose, they leave channels open to the surface that increase water infiltration and improve the subsequent growth and soil penetration of crop roots. Smaller roots decompose and leave channels through the plow plan and improve the soil penetration by the roots of subsequent crops (Williams and Weil, 2004). Most mustards have a fibrous root system, and rooting effects are similar to small grain cover crops in that they do not root so deeply but develop a large root mass more confined to the soil surface profile.

Species Rapeseed (Canola)

Two Brassica species are commonly grown as rapeseed, Brassica napus and Brassica rapa. Rapeseed that has been bred to have low concentrations of both erucic acid and glucosinolates in the seed is called canola, which is a word derived from Canadian Oil.

Annual or spring-type rapeseed belongs to the species B. napus, whereas winter-type or biennial rapeseed cultivars belong to the species B. rapa. Rapeseed is used as industrial oil while canola is used for a wider range of products including cooking oils and biodiesel. Besides their use as an oil crop, these species are also used for forage. If pest suppression is an objective, rapeseed should be used rather than canola since the breakdown products of glucosinolates are thought to be a principal mechanism for pest control with these cover crops.

Rapeseed has been shown to have biological activity against plant parasitic nematodes as well as weeds (Haramoto and Gallandt, 2004; Sattell et al., 1998). Due to its rapid fall growth, rapeseed captured as much as 120 lb. of residual nitrogen per acre in Maryland (J. Alger, personal communication, 2006). In Oregon, aboveground biomass accumulation reached 6,000 lb./A and N accumulation was 80 lb./A.

Some winter-type cultivars are able to withstand quite low temperatures (10°F) (Rife and Zeinalib, 2003). This makes rapeseed one of the most versatile cruciferous cover crops, because it can be used either as a spring- or summer-seeded cover crop or a fall-seeded winter cover crop. Rapeseed grows 3 to 5 feet tall.

Mustard

Mustard is a name that is applied to many different botanical species, including white or yellow mustard (Sinapis alba, sometimes referred to as Brassica hirta), brown or Indian mustard (Brassica juncea, sometimes erroneously referred to as canola), and black mustard [B. nigra (L.)] (Koch, 1995).

The glucosinolate content of most mustards is very high compared to the true Brassicas. In the Salinas Valley, CA, mustard biomass reached 8,500 lb./A. Nitrogen content on high residual N vegetable ground reached 328 lb. N/A (Smith et al., 2005; UC SAREP Cover Crop Resource Page). Because mustards are sensitive to freezing, winter-killing at about 25°F, they are used either as a spring/summer crop or they winter-kill except in areas with little freeze danger. Brown and field mustard both can grow to 6 feet tall.

In Washington, a wheat/mustard-potato system shows promise for reducing or eliminating the soil fumigant metam sodium. White mustard and oriental mustard both suppressed potato early dying (Verticillium dahliae) and resulted in tuber yields equivalent to fumigated soils, while also improving infiltration, all at a cost savings of about $66/acre (McGuire, 2003). McGuire (2003) provides more information about using mustard green manures to replace fumigants and improve infiltration in potato cropping systems. Mustards have also been shown to suppress growth of weeds (Boydston and Al-Khatib, 2005; Haramoto and Gallandt, 2004; Sattell et al., 1998).

Radish

The true radish or forage radish (Raphanus sativus) does not exist in the wild and has only been known as a cultivated species since ancient times. Cultivars developed for high forage biomass or high oilseed yield are also useful for cover crop purposes. Common types include oilseed and forage radish.

Daikon radish cover crop at full canopy closure
Figure 2. Daikon radish at full canopy closure, planted in August in Blacksburg, VA (Appalachian region), photographed approximately 60 days after planting. Photo credit: Mark Schonbeck, Virginia Association for Biological Farming.

Their rapid fall growth has the potential to capture nitrogen in large amounts and from deep in the soil profile (170 lb./acre in Maryland [Kremen and Weil, 2006]). Above ground dry biomass accumulation reached 8,000 lb./acre and N accumulation reached 140 lb./acre in Michigan (Ngouajio and Mutch, 2004). Below ground biomass of radishes can be as high as 3,700 lb./acre.

Oilseed radish is less affected by frost than forage radish, but may be killed by heavy frost below 25°F. Radish grows about 2 to 3 feet tall. Radishes have been shown to alleviate soil compaction and suppress weeds (Haramoto and Gallandt, 2005a; Williams and Weil, 2004).

In an Alabama study of 50 cultivars belonging to the genera Brassica, Raphanus, and Sinapis, forage and oilseed radish cultivars produced the largest amount of biomass in central and south Alabama, whereas winter-type rapeseed cultivars had the highest production in North Alabama (E. van Santen, personal communication, 2007).

Turnips

Turnips [Brassica rapa L. var. rapa (L.) Thell] are used for human and animal food because of their edible root. Turnip has been shown to alleviate soil compaction. While they usually do not produce as much biomass as other brassicas, they provide many macrochannels that facilitate water infiltration (Saini et al., 2005). Similar to radish, turnip is unaffected by early frost but will likely be killed by temperatures below 25°F.

Some brassicas are also used as vegetables (greens)

Cultivated varieties of Brassica rapa include bok choy (Chinensis group), mizuna (Nipposinica group), flowering cabbage (Parachinensis group), Chinese cabbage (Pekinensis group) and turnip (Rapa group). Varieties of Brassica napus include Canadian turnip, kale, rutabaga, rape, swede, swedish turnip, and yellow turnip. Collard, another vegetable, is a cabbage, B. oleracea var. acephala. Brassica juncea is consumed as mustard greens.

A grower in Maryland reported harvesting the larger roots of forage radish (cultivar 'Daikon') cover crop to sell as a vegetable. In California, broccoli reduced the incidence of lettuce drop caused by Sclerotinia minor (Hao and Subbarao, 2006).

Agronomic Systems

Brassicas must be planted earlier than small grain cover crops for maximum benefits, making it difficult to integrate them into cash grain rotations. Broadcasting seeding (including aerial seeding) into standing crops of corn or soybean has been successful in some regions (Krishnan et al., 1998). Brassica growth does not normally interfere with soybean harvest, although it could be a problem if soybean harvest is delayed. The shading by the crop canopy results in less cover crop biomass and especially less root growth, so this option is not recommended where the brassica cover crop is intended to alleviate compaction.

In a Maryland SARE-funded project, dairy farmers planted forage radish immediately after corn silage harvest. With a good stand of forage radish, which winter-kills, corn can be planted in early spring without tillage, resulting in considerable savings. The N released by the decomposed forage radish residues increased corn yield boost in most years (Weil, 2007). This practice is particularly useful when manure is fall-applied to corn silage fields. (For more information see SARE Project Report LNE03-192, Multipurpose Brassica cover crops for sustaining Northeast farmers).

Vegetable systems

Fall-planted brassica cover crops fit well into vegetable cropping systems following early harvested crops. White mustard and brown mustard have become popular fall-planted cover crops in the potato producing regions of the Columbia Basin of eastern Washington.

Planted in mid- to late-August, white mustard emerges quickly and produces a large amount of biomass before succumbing to freezing temperatures. As a component of integrated weed management, using brassica cover crops in vegetable rotations could improve weed control (Boydston and Al-Khatib, 2005).

Winter-killed forage radish leaves a nearly weed- and residue-free seedbed, excellent for early spring "no-till" seeding of crops such as carrots, lettuce, peas and sweet corn. This approach can save several tillage passes for weed control in early spring and can take advantage of the early nitrogen release by the forage radish. Soils warm up faster than under heavy residue, and because no seedbed preparation or weed control is needed, the cash crop can be seeded earlier than normal.

Management Establishment

Most Brassica species grow best on well drained soils with a pH range of 5.5 to 8.5. Brassicas do not grow well on poorly drained soils, especially during establishment. Winter cover crops should be established as early as possible. A good rule of thumb is to establish brassicas about four weeks prior to the average date of the first 28°F freeze. The minimum soil temperature for planting is 45°F; the maximum is 85°F.

Winter hardiness

Some brassicas and most mustards may winter-kill, depending on climate and species. Forage radish normally winter-kills when air temperatures drop below 23°F for several nights in a row. Winter hardiness is higher for most brassicas if plants reach a rosette stage between six and eight leaves before the first killing frost. Some winter-type cultivars of rapeseed are able to withstand quite low temperatures (10°F) (Rife and Zeinalib, 2003).

Late planting will likely result in stand failure and will certainly reduce biomass production and nutrient scavenging. Planting too early, however, may increase winterkill in northern zones (T. Griffin, personal communication, 2007).

In Washington (Zone 6), canola and rapeseed usually overwinter, mustards do not. Recent work with arugula (Eruca sativa) shows that it does overwinter and may provide similar benefits as the mustards (Mustard green manures). In Michigan, mustards are planted in mid-August, and winter-kill with the first hard frost, usually in October. When possible, plant another winter cover crop such as rye or leave strips of untilled brassica cover crop rather than leave the soil without growing cover over the winter (Snapp et al., 2006). In Maine, all brassica and mustards used as cover crops winter-kill (T. Griffin, personal communication, 2007).

Winter vs. spring annual use

Brassica and mustard cover crops can be planted in spring or fall. Some species can be managed to winter-kill, leaving a mellow seedbed requiring little or no seedbed preparation. For the maximum benefits offered by brassicas as cover crops, fall-planting is usually preferable because planting conditions (soil temperature and moisture) are more reliable and the cover crops produce more dry matter.

In Maryland, rapeseed and forage radish were more successful as winter- rather than spring-annual cover crops. The early-spring-planted brassicas achieved about half the quantities of biomass and did not root as deeply before bolting in spring (R. Weil, personal communication, 2007). In Michigan, mustards can be planted in spring following corn or potatoes or in fall into wheat residue or after snap beans. Fall seedings need about 90 growing-degree-days to produce acceptable biomass, which is usually incorporated at first frost (usually October). Spring seeding is less reliable due to cool soil temperatures, and its use is limited mostly to late-planted vegetable crops (Snapp et al., 2006). In Maine, brassicas are either planted in late summer after the cash crop and winter-kill, or they are spring-seeded for a summer cover crop (T. Griffin, personal communication, 2007). Rapeseed planted in late spring to summer has been used with some success in the mid-Atlantic region to produce high biomass for incorporation to biofumigate soil for nematodes and diseases prior to planting strawberries and fruit trees.

Mixtures

Mix with small grains (e.g. oats, rye), other brassicas, or legumes (e.g. clover). Brassicas are very competitive and can overwhelm the other species in the mixture. The seeding rate must be adjusted to ensure adequate growth of the companion species. Consult local experts and start with small plots or experiment with several seeding rates.

Washington farmers use mixtures of white and brown mustard, usually with a greater proportion of brown mustard. In Maryland and Pennsylvania, farmers and researchers seed the small grain and forage radish in separate drill rows rather than mixing the seed. This is done by taping closed alternate holes in the two seeding boxes of a grain drill with both small seed and large seed boxes. Two rows of oats between each row of forage radish has also proven successful (R. Weil, personal communication, 2007). Rye (sown at 48 lb./A) can be grown successfully as a mixture with winter-killing forage radish (13 lb./A).

Killing

Brassica cover crops that do not winter-kill can be terminated in spring by mowing, and/or incorporating above-ground biomass by tillage before the cover crop has reached full flower. Rolling may also be used to kill these covers if they are in flower.

Another no-till method for terminating mature brassicas is flail mowing. Be sure to evenly distribute residue to facilitate planting operations and reduce allelopathic risk for cash crops. As mentioned above, many producers incorporate brassica residues using conventional tillage methods to enhance soil biotoxic activity, especially in plasticulture systems. Brassica pest suppression may be more effective if the cover crop is incorporated.

Seed and planting

Because Brassica spp. seed may be scarce, it is best to call seed suppliers a few months prior to planting to check on availability. Brassica seeds in general are relatively small; a small volume of seed goes a long way.

  • Rapeseed (Canola): Drill 5 to 10 lb./A no deeper than ¾ in. or broadcast 8 to 14 lb./A.
  • Mustard: Drill 5 to 12 lb./A, ¼–¾ in. deep or broadcast 10 to 15 lb./A.
  • Radish: Drill 8 to 12 lb/A, ¼–½ in. deep, or broadcast 12 to 20 lb./A. Plant in late summer or early fall after the daytime average temperature is below 80°F.
  • Turnip: Drill 4 to 7 lb./A about ½ in. deep or broadcast 10 to 12 lb./A. Plant in the fall after the daytime average temperature is below 80°F.
Nutrient management

Brassicas and mustards need adequate nitrogen and sulfur fertility. Brassica sulfur (S) nutrition needs and S uptake capacity exceed those of many other plant species, because S is required for oil and glucosinolate production. A 7:1 N:S ratio in soils is optimum for growing rape, while N:S ratios ranging from 4:1 to 8:1 work well for brassica species in general.

Ensuring sufficient N supply to brassicas during establishment will enhance their N uptake and early growth. Some brassicas, notably rape, can scavenge P by making insoluble P more available to them via the excretion of organic acids in their root zone (Grinsted et al., 1982).

Brassicas decompose quickly. Decomposition and nutrient turnover from roots (C:N ratios of 20 to 30) is expected to be slower than that from shoots (C:N ratios of 10 to 20), but overall faster than that of winter rye. A winter-killed radish cover crop releases plant available nitrogen especially early in spring, so it should be followed by an early-planted, nitrogen-demanding crop to avoid leaching losses (R. Weil, personal communication, 2007).

Comparative Notes

Canola is more prone to insect problems than mustards, probably because of its lower concentration of glucosinolates. In the Salinas Valley, which has much milder summer and winter temperatures than the Central Valley of California, brassica cover crops are generally less tolerant of suboptimal conditions (i.e., abnormally low winter temperatures, low soil nitrogen, and waterlogging), and hence are more likely to produce a nonuniform stand than other common cover crops (Brennan and Smith, 2005).

Precautions

The use of brassicas for pest management is in its infancy. Results are inconsistent from year to year and in different geographic regions. Be sure to consult local expertise and begin with small test plots on your farm.

Biotoxic activity can stunt cash crop growth, thus avoid direct planting into just-killed green residue. Brassica cover crops should not be planted in rotation with other brassica crops such as cabbage, broccoli, and radish because the latter are susceptible to similar diseases. Also, scattered volunteer brassica may appear in subsequent crops. Controlling brassica cover crop volunteers that come up in brassica cash crops would be challenging if not impossible.

Black mustard (Brassica nigra) is hardseeded and could cause weed problems in subsequent crops (Boydston and Al-Khatib, 2005). Rapeseed contains erucic acid and glucosinolates, naturally occurring internal toxicants. These compounds are antinutritional and are a concern when feeding to livestock. Human consumption of brassicas has been linked to reducing incidence of cancer. All canola cultivars have been improved through plant breeding to contain less than 2% erucic acid.

Winter rape is a host for root lesion nematode. In a SARE-funded study in Washington, root lesion nematode populations were 3.8 times higher in the winter rape treatment than in the white mustard and no green manure treatments after green manure incorporation in unfumigated plots. However, populations in the unfumigated winter rape treatment were below the economic threshold both years of the study (Eberlein, 2000). For more information, see SARE Project Reports SW95-021, Brassica Green Manure Systems for Weed, Nematode, and Disease Control in Potatoes and SW02-037, Promoting Sustainable Potato Cropping Systems. Rapeseed may provide overwintering sites for harlequin bug in Maryland (R. Weil, personal communication, 2007).

Contributors: Guihua Chen, Andy Clark, Amy Kremen, Yvonne Lawley, Andrew Price, Lisa Stocking, and Ray Weil.

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 2554

Woodleaf Farm Soil Management System

Fri, 05/31/2019 - 15:50

eOrganic authors:

Carl Rosato, Woodleaf Farm

Helen Atthowe, Woodleaf Farm

Alex Stone, Oregon State University

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

Introduction

The goal of Woodleaf Farm's soil management system is to build soil organic matter and balance soil nutrients in order to produce healthy trees, optimal annual growth, and high-quality, flavorful fruit.

Woodleaf started with heavy, poorly drained soils typical of foothills pine/oak forests in this region (Overview Fig.1 Area Map). Soils were classified as NRCS capability class VII, poor for agricultural use (Overview Fig. 2 Farm Fields & Soils Map). Over time, Carl Rosato's soil building system has transformed these poor soils into fertile, well-drained soils with high organic matter content. The fundamental components of the soil management system (Table 1) include the following:

Woodleaf supplements soil nutrients with soil- and foliar-applied materials, based on soil test results.

Outcomes Soil Organic Matter

In the 1980s and 1990s, soil organic matter (SOM) ranged from 2 to 3%. From 2000 through 2014, it was 4 to 6% (Fig. 1). In the 1980s, average SOM was 2.2%. By 2014, it had climbed to 5.1%.

Over the same period, average cation exchange capacity (CEC) increased from 9.5 to 11.7 meq/100g (Fig. 2).

Soil nitrate-nitrogen (N) levels have generally decreased, from an average of 23 ppm in the early 1980s to an average of 9 ppm in 2014 (Fig. 3). Levels of total N (organic plus nitrate ammonium N) are relatively high, ranging from 4,054 ppm in the oldest field to 2,564 ppm in the youngest field (Fig. 4).

Soil Nutrient Balance

Soil samples taken since 1982 indicate that all soil macronutrients—potassium (K), phosphorus (P), calcium (Ca), and magnesium (Mg)—have increased and are generally within Woodleaf's target ranges (Table 2).

Soil levels of micronutrients have generally decreased or remained stable over the past 10 years, except for zinc (Zn), which increased from an average of 5.8 ppm in the 1980s and early 1990s to an average of 7.9 ppm in 2014 (Fig. 5) and copper (Cu), which increased rapidly to excessive levels in the late 1990s and early 2000s (17.4 – 26.1 ppm) during/after the time Cu was sprayed for peach leaf curl disease (until the early 1990s). Cu levels stabilized after spraying stooped and in 2014 averaged 5.2 ppm (Fig. 6).

Despite regular applications of foliar sulfur (S), gypsum (to add Ca and S), Solubor® (for boron, B), and manganese (Mn), some nutrients remain below Carl's targets:

Tree Growth and Nutrition

Annual tree growth ranges from 10 to 20 inches.

Leaf tissue N is in the adequate average range for peach trees (Fig. 10). Records from O'Henry peaches growing in the same field in 1994 and 2014 indicate a slight increase, from 2.4 to 2.74%.

Leaf tissue P, K, Mg, and Ca is within or above the adequate range (Fig. 10). Only leaf tissue S is below the adequate range. Levels of these nutrients in Woodleaf fruit were similar to those from two other regional organic peach farms, but all were below USDA averages.

Fruit N is at least as high as that in samples from two other organic farms in the region (Fig. 11).

Fruit levels of sodium (Na), iron (Fe), Mn, B, Cu, and Zn in Woodleaf peaches vary in comparison to those from two other organic peach farms and to USDA averages (Fig. 12).

Fruit Quality

Disease and insect damage to fruit is low.

Key Practices Living Mulch and Organic Plant Residues

Woodleaf surface-applies several kinds of plant residues throughout the year. The goal is to link N mineralization to SOM decomposition, thus avoiding nutrient loss to leaching, and to build soil C.

Organic residues applied are as follows:

Through 1991, off-farm composted cow manure with straw bedding was applied to Woodleaf's oldest fields (1, 2, and 3), at approximately 10 tons/A. In 1992, Woodleaf stopped using manure and began to bring in municipal yard waste compost.

Living Mulch

When orchards are planted or renovated, a perennial grass/clover living mulch is seeded between and beneath crop rows immediately after tillage. Seed is planted in the fall, by October 15, with a cyclone seeder.

The seed mix includes low-growing, shade- and drought-tolerant grasses, and 5% New Zealand white clover (Trifolium repens). Over time, the groundcover becomes a mix of grasses, clover, and weeds. Above-ground biomass is currently made up of approximately 70% grass species and 30% broadleaf weeds and clover. Dominant grass species include orchardgrass (Dactylis glomerata), California brome (Bromus carinatus), Blando brome (B. mollis), and tall fescue (Festuca arundinacea).

The living mulch is mowed two to four times annually. The height of the living mulch before each mowing ranges from 1 to 3 feet. On average, approximately 2-4 tons/A of hay mulch (dry weight) are added to the soil surface each year.

The living mulch residue has not been analyzed for nutrient content, and seasonal/annual variation is likely. However, an approximate nutrient contribution can be estimated, based on published averages for mixed grass hay (Parnes, 1990). Table 3 shows the approximate nutrient contribution from 2 tons/A of mowed living mulch (dry weight).

Clover in the living mulch adds some N through N-fixation. The other nutrients are taken up from and returned to the soil. Regular mowing allows these nutrients to be continually recycled.

The year-round growing roots of the living mulch also reduces N-leaching by the winter rains common in northern California and may help to retain other nutrients prone to leaching, such as S, Ca, Mn, and B.

Chipped Branches

Green leaves and young branches are applied to the soil after pruning in late summer/fall and spring. Branches are from 0.5 to 1.25 inches in diameter. These materials have a higher carbon to nitrogen ratio (C:N) and degrade more slowly than the living mulch.

Pruned branches are placed in row middles over the living mulch. They are broken up first with a rotary tractor-mounted mower and then mowed again with a small riding mower and blown beneath trees (see soil/insect management video).

Off-Farm Yard Waste Compost

Carl purchases yard waste compost from a municipal composting facility 20 miles from the farm. Compost consists of grass clippings and branch/leaf prunings that have been aerobically composted with a bed turner.

Compost is applied two to four times per year, usually in spring and fall. The current rate is 2 tons/A (dry weight) per application. In the past, 4-6 tons/A were applied annually. As soil fertility increases, Woodleaf is experimenting with reduced rates.

Compost is applied primarily to row middles with a compost spreader. Some is blown under trees. Compost is irrigated into the living mulch immediately following application.

Nutrient analysis of off-farm yard waste compost is shown in Table 4.

No-till/Reduced Tillage

Tillage is an important part of many organic farming systems that utilize plant residues for soil fertility management, particularly annual horticultural systems. However, tillage is used very little at Woodleaf.

Tillage occurs only when fields are brought into cultivation or during renovation and replanting (every 20 or 21 years). At all other times, organic residues and fertilizers are surface-applied and usually not incorporated. Some fields have not been tilled for 21 years.

During field renovation, a front end loader is used to pry out tree stumps and remove them from the orchard. To break up the understory sod, three passes are then made using a box scraper with five rippers lowered to 8 inches.

Soil Mineral Balancing

Soil mineral (nutrient) balancing is a foundation of Woodleaf's soil management system (Table 1). Carl's system is based on years of farming experience and on research and recommendations by Neal Kinsey. Soil nutrients are supplied primarily through application of organic materials and supplemented with off-farm, purchased minerals when soil tests indicate they are needed.

Mineral Amendments

The need for mineral amendments is indicated when soil analysis shows levels of nutrients below targets (Table 2). Minerals are surface applied or incorporated at planting or during field renovation.

The targets Woodleaf is working hardest to achieve are:

  • Boron: Despite annual B applications of 10 lb/A for more than 15 years, soil B remains below Carl's target of 0.8 ppm (Fig. 7). Carl has limited annual B rates to a maximum of 10 lb/A. However, he is considering raising this ceiling.
  • Sulfur: Gypsum is applied each spring at 250 lb/A. Nonetheless, soil S is still below Carl's target of 20 ppm (Fig. 8).

The following minerals are also regularly applied:

  • Calcium: In the past, Ca was added as limestone. Currently, annual gypsum application at 250 lb/A helps increase the Ca portion of cation balance, while reducing the Mg portion, currently 18% (Fig. 13, Fig. 14, and Fig. 15). For information on how Carl calculates Ca and Mg rates, see Calcium and Magnesium Amendment Calculation below.
  • Manganese: Despite regular Mn applications, soil Mn remains below Carl's target of 15 ppm (Fig. 9).

Minerals are also applied annually as a foliar mineral mix.

Carl's soil test results, mineral balancing targets, and inputs are presented in Table 2.

Calcium and Magnesium Amendment Calculation

Carl's formula to determine Ca and Mg application rates is:

  • Ca rate (lb/A) = [CEC x target %Ca (68%) x 400] – current soil Ca (lb/A)
  • Mg rate (lb/A) = [CEC x target %Mg (12–18%) x 240] – current soil Mg (lb/A)

Sample Ca calculation for a soil with a CEC of 10.0 and Ca of 1,060 ppm:

  1. Convert from ppm (as reported on soil tests) to lb/A. Multiply ppm by two: 1,060 x 2 = 2,120 lb Ca.
  2. Insert the formula: 10 x 0.68 x 400 = 2,720 lb Ca needed to reach the target. Current soil Ca is 2,120 lb/A, so 600 lb/A Ca needs to be applied (2,720 – 2,120 = 600 lb).
  3. A ton of limestone generally contains 600 lb Ca (depending on source), so 1 ton/A lime is needed to raise soil Ca to 68%.
Analysis: Integrating Practice and Research

The goal of an organic soil management system is to build SOM and enhance soil microbial activity, rather than relying 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, C, and N inputs (Fierer, 2009; Kallenbach, 2011). Research has shown that total C content (Drinkwater, 1998; Kong, 2005) and/or lability (ease of decomposition) of organic matter (Marriott, 2006; Smukler, 2008; Kallenbach, 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.

Woodleaf Farm applies several kinds of plant residues throughout the year—mowed living mulch, chipped branches, and yard waste compost. These materials vary in how easily their C is degraded. Overall, however, Carl maintains high levels of C in proportion to N, with the following results:

  • N and other nutrients are supplied gradually from the reservoir of SOM as crops need them.
  • Leaching losses are minimized due to gradual N mineralization.
  • The microbial community is dominated by fungi, which flourish during early stages of residue breakdown.
  • Carl balances the high-C organic materials with green organic matter by regularly mowing the living mulch. This prevents N immobilization, which could be a problem if too much C were applied.
  • Woodleaf's N and C cycling system works in a synergistic manner with its biological insect pest management system.
System Evaluation

In 2014, Woodleaf evaluated its apparently successful N-cycling system by looking at fruit quality, leaf tissue nutrient concentrations, soil organic N, and other soil nutrient levels. Small sample sizes were used in this evaluation; funding for a more complete evaluation with larger sample sizes would be preferable.

Method

Woodleaf performed fruit tissue analysis on three random samples (two fruits per sample) of O'Henry peaches from field 2 (in a location where the same variety had been replanted and grown since 1985). Results were compared to three random samples (six fruits) of O'Henry peaches from two other successful long-term organic farms in northern California. Results were also compared to the USDA average nutritional content for peaches.

Leaf tissue samples were taken from the same rows as the fruit samples. Carl compared results to tissue nutrient concentrations in O'Henry peach trees from the same field in 1994 and to normal average ranges reported by A&L Western Laboratories, Modesto, California.

Soil samples were taken from the same rows (0- to 12-inch depth). Soil was also sampled in four other fields. Soil was analyzed for organic N (total Kjeldahl N – ammoniacal N) and nitrate-N. Trends were plotted for the period 1982–2014.

Analysis

In 2014, Woodleaf recorded a very good yield and the most economically successful year in its 34-year history. No insecticides were applied to peaches, pears, or apples, yet insect and disease damage was less than 10%.

  • Fruit tissue N: Fruit tissue N (mg/100g) was at least as high as that of fruit samples from the other two farms (Fig. 11).
  • Leaf tissue N: Leaf tissue N was in the adequate range and appears to have increased slightly since 1994 (Fig. 10).
  • Soil N: SOM has increased, while soil nitrate-N has decreased (especially in field 1, where manures and fish meal were applied until 1992) (Fig. 1 and Fig. 3).  In recent years, nitrate-N has been relatively low (averaging 9 ppm in 2014). But, organic N is now relatively high (Fig. 4).
Conclusions

Based on long-term soil test data (1982-2014), fruit, leaf tissue, and soil data (2014); low insect and disease damage (2013–2014); and financial success (2013–2015), it seems that Woodleaf's long-term use of high-C/low-N soil amendments and reduced tillage is maintaining soil health, yield, and fruit quality.

More research is needed on working farms to test the relationships among organic soil management practices, soil health, yield, and crop quality. Nevertheless, there is some scientific support for Woodleaf's success with high-C/low-N amendments.

One study conducted not far from Woodleaf (in central California) compared 13 tomato fields on 13 organic farms. Each farm used different soil amendments with different N-cycling scenarios. Some used mostly manure (higher N), while others used mainly composted yard waste (higher C). Yields were similar on all 13 farms. However, manure application was associated with increased Olsen P, increased gram-positive and gram-negative bacteria, and decreased fungal and mesofaunal markers (Bowles, 2014). Other studies report that higher P may negatively affect soil fungi abundance and activity (Fierer, 2009; de Vries, 2012). Soil management practices that support healthy soil fungal communities have been suggested as a way to increase N retention and other soil ecosystem functions (de Vries, 2012; Jackson, 2012).

It is likely that other parts of Woodleaf's soil system are just as important, especially reduced tillage and possibly mineral balancing. Several researchers have shown that tillage decreases soil microorganisms, specifically soil fungi (Calderón, 2000; Minoshima, 2007; Young-Mathews, 2010).

This article was developed with support from USDA's National Institute of Food and Agriculture through the Western Sustainable Agriculture Research and Education program under grant number SW13-017.

  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 14132

Managing Cucumber Beetles in Organic Farming Systems

Fri, 05/31/2019 - 15:42

eOrganic author:

William E. Snyder, Department of Entomology, Washington State University - Pullman

This article examines the biology and management of cucumber beetles within organic farming systems.

Cucumber Beetle Biology

In North American cucurbit crops, two species of cucumber beetle present the most problems. These are the striped cucumber beetle (Aclymma vittatum in the eastern U.S. and A. trivittatum in the west) and the spotted cucumber beetle (Diabrotica undecimpunctata). Adults of the two species are easy to tell apart: the spotted cucumber beetle is somewhat larger and has dark black spots (Fig. 1a), whereas the striped cucumber beetle has long black stripes down its back (Fig. 1b).

Figure 1. Western spotted cucumber beetle (Diabrotica undecimpunctata undecimpunctata) and striped cucumber beetle (Acalymma vittatum)
Figure 1. Cucumber beetles. (a) western spotted cucumber beetle (b) Striped cucumber beetle. Photo credits: (a) Susan Ellis, Bugwood.org; (b) Clemson University - USDA Cooperative Extension Slide Series, Bugwood.org.

The western corn rootworm (Fig. 2) is related to cucumber beetles, and looks similar to the striped cucumber beetle. Although it is often observed on cucurbit crops, it causes little or no damage to them, and so it is important to correctly identify the insect in your crop. Striped cucumber beetles have black abdomens below, and pale colored legs with black "knees"; the western corn rootworm has a pale-colored abdomen and more uniformly dark legs. The black stripes on the backs of striped cucumber beetles are more distinct and exend to the tip of the wings (Delahaut, 2010; Burkness and Hutchison, 2011).

Figure 2. Western corn rootworm (Diabrotica virgifera virgifera).
Figure 2. The western corn rootworm is similar in appearance to the striped cucumber beetle, and is often observed on squash crops, but is not a squash pest. Photo credit: Winston Beck, Iowa State University, Bugwood.org.

Cucumber beetle adults generally overwinter in residue from the previous years’ cucurbit crops, or nearby. The adults first move into cucurbits in the spring and then throughout the summer, feeding on stems, foliage and flowers.

Differences between striped and spotted cucumber beetles

Despite their many similarities, there are some differences between striped and spotted cucumber beetles. Spotted cucumber beetles feed on over 200 different crop and non-crop plants, whereas striped cucumber beetles have a much stronger preference for cucurbits and rarely feed on other plants. Spotted cucumber beetles seem to be more of a pest farther south in the US, whereas striped cucumber beetles dominate farther north. Striped cucumber beetles lay eggs at the base of cucurbit plants and their larvae then feed on the roots of these plants. The spotted cucumber beetle is very different, primarily laying its eggs on corn and other grasses such that the larvae of spotted cucumber beetles are not damaging to cucurbit crops. Once the eggs hatch, the larvae spend several weeks feeding on root tissue. Thus, damage by the larvae might not be obvious just from looking at aboveground foliage—unless one attempts to pull up a plant and finds little resistance due to roots having been eaten! Larvae then pupate in the soil for about a week before emerging as adult beetles.

Cucumber beetle crop damage to cucurbit crops

Cucumber beetles damage cucurbit crops in at least three ways. First, their feeding directly stunts plants and, when flowers are eaten, can reduce fruit set (Fig. 2A). Second, cucumber beetles transmit bacterial wilt disease (Erwinia tracheiphila). More information on bacterial wilt can be found in this APSNet article on Bacterial Wilt and this Cornell Vegetable MD Online fact sheet on Cucumber Beetles, Corn Rootworms and Bacterial Wilt in Cucurbits. Third, adults scar the fruit reducing its marketability (Fig. 2B). It is primarily young cucurbit plants that are vulnerable to stunting and bacterial wilt disease, whereas damage to older plants primarily comes from fruit scarring. In fact, older plants can tolerate as much as 25% defoliation due to beetle feeding with no reduction in yield (Hoffmann et al., 2002, 2003).

Natural Enemies of Cucumber Beetles on Organic Farms Predators

wolf spider and carabid beetle
Figure 2. Predators that feed on cucumber beetles include (a) wolf spiders and (b) ground beetles. Photo credit: (a) Whitney Cranshaw, Colorado State University, Bugwood.org (b) John Goulet, Canadian Biodiversity Information Center.

Adult cucumber beetles are relatively large, by insect standards, and have a hard outer shell and so will mostly be fed upon by relatively large predators. Wolf spiders (Fig. 3A) have been shown to feed heavily on cucumber beetles in cucurbit crops (Snyder and Wise, 2001). Also, cucumber beetles avoid wolf spiders, and feed less when spiders are around even when the spiders do not actually kill the cucumber beetles (Snyder et al., 2001; Williams and Wise, 2003). Ground beetles (Fig. 3B) sometimes also feed on adult cucumber beetles (Snyder and Wise, 2001), as do other big predators such as bats (Whitaker, 1995).

A recent study searched for DNA of a cucumber beetle relative, the western corn rootworm, in the stomachs of predatory insects and spiders (Lundgren et al., 2009). The researchers believed that most of the beetle DNA that they recovered inside predators came from beetle eggs and larvae. This study found an incredible array of different predator species eating the beetles, including harvestmen (“daddy long legs”), ground and rove beetles, spiders of several kinds, and predatory mites. So, a bio-diverse community of predators may be important for biological control of cucumber beetles, rather than relying on any single predator species. Strategies to conserve predators are presented in the article, Farmscaping: Making Use of Nature’s Pest Management Services.

Insect pathogens

Most insect pathogens live in the soil, and so would most likely be effective against the root-feeding cucumber beetle larvae. Fungal pathogens and insect-attacking nematodes are both commercially available as bio-pesticides, and soil drenches of these bio-insecticides have shown some activity against cucumber beetle larvae feeding on roots (Reed et al., 1986; Choo et al., 1996; Ellers-Kirk et al., 2000). However, there is no evidence that insect pathogens effectively control adult cucumber beetles.

Parasitoids

A tachinid fly and a braconid parasitoid wasp parasitize striped cucumber beetle, and both sometimes have large impacts on striped cucumber beetles (Smyth and Hoffmann, 2010). There is some anecdotal evidence that parasitoid populations may build up over several years in organic fields, such that parasitoid impacts in organic fields may be far greater than in conventional fields. Both the fly and wasp parasitoid live inside the insect and so unfortunately there is no way to easily assess parasitoid numbers, other than rearing cucumber beetles in a cage until the parasitoids emerge.

Organic Cultural Controls for Cucumber Beetles

Organic-approved insecticides have not always been found to be effective (see below), so cultural controls may be the best option for many organic farmers. Cultural controls include crop rotation, the use of transplants rather than direct seeding, row covers, trap cropping, mulching for predator conservation, the use of reflective plastic mulches, choosing resistant varieties, and intercropping:

Rotate cucurbit crops

Cucumber beetles often overwinter near to the previous years’ cucurbit crop. So, one way to reduce pest problems the next year is to plant cucurbits as far away from last year’s crop as possible. Any barriers between last-year’s planting site and this year’s, such as hedgerows and out-buildings, may help slow beetle colonization of the new crop. However, the beetles are highly mobile and so crop rotation alone is unlikely to entirely control cucumber beetles.

Transplant rather than direct seed

Seedlings and small plants are most susceptible to cucumber beetle feeding damage and to bacterial wilt (Yao et al., 1996; Hoffmann et al., 2002, 2003). Using transplants avoids exposure to cucumber beetle feeding during the most susceptible plant stages. This also reduces the total time that cucurbit plants are in the field each season, providing less time for cucumber beetle densities to build and for disease symptoms to develop.

Use floating row covers

Floating row covers provide the most reliable defense against cucumber beetles, when left in place until flowering begins (row covers must eventually be removed to allow bees and other pollinators to visit the flowers). Downsides of row covers include their high cost and the fact that they block access to the crop for weeding. Plastic or other mulches may be combined with floating row covers to reduce these weed problems, provided that the plastic mulch is removed from the field at the end of the growing season.

Plant perimeter trap crops

With good crop rotation practices, adult cucumber beetles will always be moving into a crop from somewhere else. In perimeter cropping the main cucurbit crop is ringed by plantings of a different, highly attractive cucurbit variety. Cucumber beetles generally aggregate at field edges regardless (Luna and Xue, 2009), and attractive trap crops may further accentuate this tendency. Recent research indicates that the Blue Hubbard and buttercup varieties of Cucurbita maxima, and zucchini (C. pepo), are particularly attractive to cucumber beetles (Adler and Hazzard, 2009). Then, approved insecticides can be applied to the trap crop only, reducing total insecticide use (Cavanagh et al., 2009). Lists of highly attractive cucurbits are presented in this ATTRA publication on Cucumber Beetles (fee may apply) , and a research project funded by the USDA's Sustainable Agriculture Research and Education program generated detailed recommendations for using this strategy in cucurbits.

Apply straw mulch

Straw mulch can help reduce cucumber beetle problems in at least 3 different ways. First, mulch might directly slow beetle movement from one plant to another (Cranshaw, 1998; Olkowski, 2000). Second, the mulch provides refuge for wolf spiders and other predators from hot and dry conditions, helping predator conservation (Snyder and Wise, 2001; Williams and Wise, 2003). Third, the straw mulch is food for springtails and other insects that eat decaying plant material; these decomposers are important non-pest prey for spiders, helping to further build spider numbers (Halaj and Wise, 2002). It is important that straw mulch does not contain weed seeds and to make certain that it does not contain herbicide residues which can take years to fully break down.

Use reflective plastic mulches

Results of a study in Virginia (Caldwell and Clark, 1998) suggest that metallic-colored plastic mulches repel cucumber beetles, reducing beetle feeding damage and the transmission of bacterial wilt.

Use organic mulches

Cucumber plants grown in richly-mulched soils harbor fewer cucumber beetles than do those in soils with less organic content (Yardim et al., 2006), perhaps because organic matter fosters diverse populations of beneficial soil microorganisms that trigger the plants internal defenses (Zehnder et al., 1997).

Plant resistant/unattractive cucurbit varieties

Cucumber beetles are attracted to host plants by a chemical called cucurbitacin, which gives cucurbits their bitterness and likely is used as a defense against less-specialized herbivores (Deheer and Tallamy, 1991). The beetles absorb cucurbitacin into their bodies and use it to defend themselves against predators and pathogens (Gould and Massey, 1984; Tallamy et al., 1998). So, cucurbit varieties or species with lower cucurbitacin levels may be less attractive to cucumber beetles. Of course, market forces largely determine which cucurbits are planted, so variety selection will not be possible in many situations. Cucurbits are listed by their attractiveness to cucumber beetles in Cucumber Beetles: Organic and Biorational Integrated Pest Management .

Intercropping

A field-plot trial found that intercropping cucumbers with corn and broccoli reduced striped cucumber beetles substantially, compared to plots planted in a monoculture of cucumber (Bach, 1980). In this study intercropping also reduced the incidence of bacterial wilt disease. A recent study suggests that intercropping watermelons or musk melons with radish, nasturtium, tansy, buckwheat, cowpea or sweet clover has a similar benefit (Cline et al., 2008), suggesting that many different types of intercrops can help reduce cucumber beetle densities on cucurbits. 

Organic Chemical Controls for Cucumber Beetles

Field trials have reported somewhat inconsistent success using organic-approved insecticides to control cucumber beetles. To entirely block wilt transmission, insecticides would have to be applied repeatedly as new beetle colonists arrive, which could grow expensive. Treatment of plants just before they are transplanted into the field could help get the plants past the vulnerable early stages (Yao et al., 1996). 

IMPORTANT: Before using any pest control product in your organic farming system:

  1. read the label to be sure that the product is labeled for the crop and pest you intend to control,
  2. read and understand the safety precautions and application restrictions, and
  3. make sure that the brand name product is listed in your Organic System Plan and approved by your USDA-approved certifier.

If you are trying to deal with an unanticipated pest problem, get approval from your USDA-accredited certifier before using a product that is not listed in your plan; doing otherwise may put your organic certification at risk. Note that, although OMRI and WSDA lists are good places to identify potentially useful products, all products that you use MUST be approved by your USDA-accredited certifier. For more information on how to determine whether a pest control product can be used on your farm, see the related eOrganic article, Can I Use This Input on My Organic Farm?

Kaolin clay is reported to act by making cucurbit crops unattractive to cucumber beetles and because it gums up the beetles’ antennae and otherwise irritates them.

Pyrethrum is a naturally occurring broad-spectrum insecticide extracted from the dried flower heads of African chrysanthemums. Pyrethrum will kill both pests and beneficials, and so should be used with caution. One approach to reduce harm to beneficials is to treat only the perimeter trap crop with pyrethrum, or only particular hotspots within the main crop.

Spinosad is a general feeding deterrent and toxin. Some effectiveness has been reported in controlling cucumber beetles, although label instructions should of course always be followed. Not all spinosad formulations are organic-approved, so care must be taken in selecting any chemical used.

Other Organic Control Options

No doubt reflecting just how difficult cucumber beetles can be to control, particularly within organic farming systems, a few other more unusual approaches have been attempted with a degree of success. Both of the approaches below provide the satisfaction of instantly removing cucumber beetles.

Flaming using standard weed flamers is one way to kill cucumber beetles, although clearly this would only be used on a trap crop and not the main crop. This approach may be less effective, though, with striped cucumber beetles, which often concentrate their feeding at the base of plants, and frequently head down into the soil when disturbed.

Sucking up beetles using a vacuum (e.g., D-vac suction sampler) or a reversed leaf-blower can be an effective way to remove adult beetles, in particular from trap crops where a limited area needs to be treated (Fig. 3). It would be challenging to suck any substantial fraction of beetles from a large area.


Figure 3. A hapless undergraduate worker demonstrates the use of the D-vac bug vacuum, which can be used to suck cucumber beetles out of a cucurbit crop. Photo credit: Bill Snyder, Washington State University. 

Region-specific Information on Cucumber Beetle Biology

NOTE: Most of the controls described on these links ARE NOT ORGANIC APPROVED, although the details of local cucumber beetle biology are relevant to organic farming systems.

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  • Williams, J.L, and D.H. Wise. 2003. Avoidance of wolf spiders (Araneae: Lycosidae) by striped cucumber beetles (Coleoptera: Chrysomelidae): laboratory and field studies. Environmental Entomology 32: 633–640. Available online at: http://dx.doi.org/10.1603/0046-225X-32.3.633 (verified 11 March 2012). 
  • Yao, C. B., G. Zehnder, E. Bauske, et al. 1996. Relationship between cucumber beetle (Coleoptera: Chrysomelidae) density and incidence of bacterial wilt of cucurbits. Journal of Economic Entomology 89: 510–514. (Available online at: http://dx.doi.org/10.1093/jee/89.2.510 510-514"> http://dx.doi.org/10.1093/jee/89.2.510 510-514) (verified 11 March 2012).
  • Yardim, E. N., N. Q. Arancon, C. A. Edwards, T. J. Oliver, and R. J. Byrne. 2006. Suppression of tomato hornworm (Manduca quinquemaculata) and cucumber beetles (Acalymma vittatum and Diabotrica undecimpunctata) populations and damage by vermicomposts. Pedobiologia 50: 23–29. Available online at: http://dx.doi.org/10.1016/j.pedobi.2005.09.001 (verified 11 March 2012).
  • Zehnder, G., J. Kloepper, C. B. Yao, and G. Wei. 1997. Induction of systemic resistance in cucumber against cucumber beetles (Coleoptera: Chrysomelidae) by plant growth-promoting rhizobacteria. Journal of Economic Entomology 90: 391–396. Available online at: http://dx.doi.org/10.1093/jee/90.2.391 (verified 11 March 2012).

 

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 5307

Including Barley in Organic Poultry Diets

Wed, 05/22/2019 - 09:35

eOrganic author:

Dr. Jacquie Jacob Ph.D., University of Kentucky

NOTE: Before using any feed ingredient make sure that the ingredient is listed in your Organic System Plan and approved by your certifier. If you intend to feed barley to organic poultry, the barley must be certified organic.

Introduction

Barley (Hordeum vulgare) is commonly grown for malting, but can also be grown for food and animal feed. It is the main feed ingredient in some parts of western North America, and in many European countries that are less suitable for growing corn. Barley can also be grown as a pasture crop.

Barley can play an important role in crop rotation in organic production systems. It has an extensive root system that makes it able to compete with weeds; and is often used to break disease, insect, and weed cycles associated with other crops. Direct rotation with other small grains is not recommended when there are alternatives available. The small grains left behind can harbor disease or insect pests (Brown, 2003).

 

Cultivars

There are several different varieties of barley that can be classified in a number of ways:

  • Barley varieties can be classified based on head type. There are 2-row and 6-row varieties classified on the basis of the number of seeds on the stalk of the plant. The 2-row varieties are grown primarily in Europe because they are most adapted to drier climates. The 6-row varieties are commonly grown in the United States. Six-row varieties are typically higher in protein and lower in starch than 2-row varieties (Jeroch and Danicke, 1975).
  • Barley varieties can also be classified based on growth habit. There are winter and spring barley types in both the 2-row and 6-row varieties. Winter barley requires the seedlings to be exposed to cold in order to produce heads and grains normally. Therefore, winter barley is usually sown in the fall so that it will be exposed to low temperatures during the subsequent winter. Spring barley does not have the requirement for cold temperatures, so it can be sown in the spring and summer. Spring barley can play an important role in crop rotation with non-grain crops and is especially useful as it tends to break disease, insect, and weed cycles associated with other crops (Brown, 2003).
  • Waxy versus normal barley varieties differ in the composition of the starch content. The level of amylose to amylopectin is an important characteristic that affects malting, food, and feed value. Normal barley varieties contain about 27% amylose and 73% amylopectin. Waxy starch varieties have lower amylose (2-10%) and higher amylopectin (90-98%) content. Amylopectin is easier to digest than amylose.
  • Barley is typically eaten after the inedible, fibrous outer hull has been removed. Once the hull has been removed it is referred to as dehulled barley. Dehulled barley still has its bran and germ. Pearl barley is dehulled barley that has been steam-processed to remove the bran. The proportion of hull to kernel can differ widely between varieties, resulting in a wide variation in the energy content. Dehulled barley should not be confused with hull-less, or naked barley. Hull-less barley looks like hulled barley while it is growing, but as it begins to mature the hull loosens. The grain is completely removed during harvest.
  • Hull-less, or naked barley, is closely related to hulled, or covered barley. While hulled barley contains 5-6% crude fiber, the fiber levels of hull-less barley are similar to those of wheat and corn. Both hulled and hull-less barley contain beta-glucans. While the available energy content of hull-less barley is less than corn, it is superior to hulled barley.
Nutrient Composition

Nutrient content of barley (Batal and Dale, 2010)

  • Dry matter: 89%
  • Metabolizable energy: 2750 kcal/kg (1250 kcal/lb)
  • Crude protein: 11.5%
    • Methionine: 0.18%
    • Cysteine: 0.25%
    • Lysine: 0.53%
    • Tryptophan: 0.17%
    • Threonine: 0.36%
  • Crude fat: 1.9%
  • Crude fiber: 5.0%
  • Ash: 2.5%
    • Calcium: 0.08%
    • Total phosphorus: 0.42%
    • Non-phytate phosphorus: 0.15%

The available energy content of barley grain can vary widely, largely due to the presence of beta-glucans. Beta-glucans (ß-glucans) are referred to as "anti-nutritional factors" because inclusion of feedstuffs containing ß-glucans depresses nutrient digestion in poultry. The chemical structure of ß-glucans makes it difficult for poultry to digest. The ß-glucans combine with water in the intestine to form a gel that increases the thickness–or viscosity–of the intestinal contents, resulting in reduced nutrient availability. The increased viscosity can also result in increased instances of 'pasty vents' in chickens, especially chicks. Beta-glucan levels in barley are affected by the cultivar, growing conditions, geographic location, condition at harvest, and storage conditions. Commercial feed enzymes (ß-glucanase) that break down ß-glucans in the diet are now available. The enzymes reduce the viscosity of the intestinal contents and improve bird performance.

Barley also contains phytic acid, which binds phosphorus and thus reduces phosphorus availability to the animal. Compared to other grains, however, the level of phytate in barley is less than that in wheat and oats, but higher than that in rye (Bartnick and Szafrańska, 1987). The enzyme phytase is needed to break down phytate and release the bound phosphorus. Poultry are not able to produce enough phytase. Cereals do contain some phytase since it is needed to make the phosphorus available to the embryo after germination. Phytase activity is very low in most feed ingredients although slightly higher in barley, rye, triticale, wheat, and wheat byproducts (Weremko et al., 1997). However, the phytase present has not been shown to increase phosphorus availability in poultry. Low-phytate barley varieties have been developed. The phosphorus bioavailability of these low-phytate varieties is 49%, compared to 28% in normal barley. When low phytate barleys are used in poultry diets, the need for supplemental phosphorus is reduced by 50% (Salarmoini et al., 1998). In addition, use of the low-phytate varieties has been shown to increase the bioavailability of other minerals such as zinc (Linares et al., 2007).

Energy

The main component of barley grain is starch, which is the main source of energy in grains. The level and availability of the starch will affect the energy content of a cereal grain. Barley has about 60% starch on a dry matter basis (Knudsen, 1997). Starch is comprised of linked glucose (a sugar) molecules connected together, and is referred to as a polysaccharide (meaning many sugars). The connection is via α-glycosidic links that are easily broken down in the digestive tract of birds and mammals. Polysaccharides are identified by the carbon atoms of each sugar involved in the link, as well as the type of linkage involved. There are two types of linkages–alpha (α) and beta (ß)–which differ in orientation of the oxygen atom involved in the linkage. The majority of the glucose linkages in starch are α-(1→4) linkages, although there are also a few α-(1→6) linkages. These α-(1→4) and α-(1→6) linkages are easily digested by the enzymes produced in the digestive system of animals. Animals are also able to digest the α-(1→2) linkages between glucose and fructose in sucrose, the ß-(1→4) linkage between glucose and galactose in lactose, and the α-(1→1) linkages between glucose molecules. Animals are not able to digest any of the other glycosidic bonds.

There are two main classes of cereal starches: amylose and amylopectin. They have different size, shape and composition. The glucose molecules of amylose are connected to each other in linear chains with α-(1→4) linkages. In amylopectin, the chains of α-(1→4) linked glucose are connected in a highly branched structure with α-(1→6) linkages between the chains. Amylopectin is easier to digest than amylose, so the digestibility of starch in a grain depends on the type of starch present. Normal barley varieties contain about 27% amylose and 73% amylopectin. Waxy starch varieties have lower amylose (2-10%) and higher amylopectin (90-98%) content. Digestibility of waxy starch in barley has been reported to be 10% higher than for normal starch (Ankrah et al., 1999), but waxy barley grains are typically smaller and contain less starch (Tester and Morrison, 1992). In addition, waxy barley varieties have also been shown to contain more ß-glucan than normal varieties (Ankrah et al., 1999).

The other source of energy in cereal grains is lipid. With 2-3% oil, the lipid content of barley is relatively low. Some cultivars, however, have been developed with increased lipid content. This increase in lipid is associated with increased lysine. The main fatty acid present is linoleic acid.

Protein

As with most cereal grains, the protein content of barley is low compared to legume seeds (Shewry and Tatham, 1990). Cereals contain three types of proteins: storage proteins, structural and metabolic proteins, and protective proteins. The majority of the proteins in cereal grains are storage proteins–in particular, prolamins and globulins. Prolamins are rich in the amino acids proline and glycine but are low in the essential amino acids lysine and tryptophan. Prolamins represent about half of the total protein present in barley, as well as corn, millet, rye, sorghum, and wheat. The primary prolamin in barley is hordein. Barley proteins are low in many of the essential amino acids including lysine, threonine, methionine and histidine.

The protein content of barley varies depending on the variety and growing conditions (Griffey et al., 2010). For example, 6-row cultivars are typically higher in protein than 2-row varieties. Nitrogen fertilization increases the protein content of barley grain, but the relative levels of the essential amino acids decrease.

Inclusion in Poultry Diets Feeding Ground Barley

While corn is typically used in poultry diets in the United States, Canada and many countries in Europe have been using wheat and barley for many years. Of course, the level of use will vary depending on the market prices and local conditions. Wheat and barley are lower in energy than corn, so it is common to add fat to poultry diets based on these grains in order to achieve the high dietary energy levels used in commercial poultry production (Adams, 2001). Such diets can increase the viscosity of the intestinal contents and increase the moisture content of the litter. Wet litter results in increased ammonia levels in the poultry house, as well as an increased incidence of breast blisters and hock burns on meat-type birds.

Nutritionists use nutrient composition tables to formulate least-cost rations that meet the nutrient requirements of animals. The wide variation observed in the energy content of barley, however, is not reflected in table values but needs to be taken into consideration when formulating diets. While many research reports in the literature are contradictory, it is generally recommended that unsupplemented barley should not be used in starter diets, and that the use of barley in poultry diets be restricted to 20%. The use of feed enzymes reduces the need for these restrictions.

The use of feed enzymes in barley-based diets reduces intestinal viscosity, thus improving the feeding value of barley. Enzyme supplementation also reduces the variation in feeding value seen with unsupplemented barley-based diets. Feeding barley cultivars of widely different ß-glucan levels give similar growth performance when supplemented with dietary enzymes. A variety of different feed enzymes are available that have ß-glucanase activity. Using enzymes also improves the litter quality of poultry raised on barley-based diets. Today, near-infrared spectrometry (NIRS) has made it easier to identify which batch of barley would benefit from enzyme supplementation and which would not. Near-infrared spectrometry is a rapid, computerized system that can be used for analyzing feed ingredients. It uses infrared light instead of chemicals for the analysis. The analysis requires that the system be calibrated for the particular ingredient being tested–so may be more expensive for some of the less commonly used ingredients–but has been routinely used in some feed mills for corn, wheat and barley.

Feeding Whole Barley

Feeding whole grain in a complete feed has gained popularity in some regions as it can reduce feed-handling costs by eliminating the need for grinding. When using whole barley to replace all or a part of the grain in the diet, it is necessary to balance grains with the other ingredients so that the whole grain does not dilute the total nutrients consumed by the birds.

Feeding up to 20% whole barley to broilers had no negative effects on growth rate (Biggs and Parsons, 2009). Feeding 35% or more whole barley grain resulted in reduced growth and feed efficiency initially, but this reduced growth rate resulted in lower mortality and instances of leg problems.

Feeding 20% whole barley to turkeys resulted in an early reduction in growth rate (<1% reduction) as well as lower flock mortality and improved skeletal health (Bennett et al., 2002).

Reports of Bennett and Classen (2003) concluded that feeding whole barley (60%) blended with a mash concentrate to laying hens reduced egg production, feed efficiency, and shell quality while increasing feed intake, egg weight and body weight gain. They found this to be contrary to positive results found when choice feeding was used, and speculated that when the grain and concentrate are fed together, the hens can no longer accurately select intakes of whole grains and concentrates that meet their individual nutritional needs.

Summary
  1. Barley grains are lower in energy than corn but higher in protein.
  2. Barley grains contain ß-glucans which adversely affect nutrient availability.
  3. Supplementing barley-based poultry diets with ß-glucanase enzyme increases the level of barley that can be included in the diet without adversely affecting performance. The level of beta-glucanase enzyme required will depend on the age of the bird as well as the barley cultivar used.
  4. Care must be taken when using barley in starter diets. Older birds are better at using barley than young chicks.
  5. Barley grains contain phytate, which makes most of the phosphorus present unavailable. The use of phytase enzymes increases phosphorus availability and reduces the need for supplemental phosphorus. This results in increased phosphorus utilization, thus reducing fecal loss of phosphorus and consequently less damage to the environment.
Byproducts Brewer's Dried Grains

Brewer's dried grains are a byproduct of making wort or beer. They are also sometimes referred to as spent grain. They include cellulose and hemicellulose as well as the protein remaining after barley has been malted to releases its sugar for brewing. Sugars and starches in the original grain are removed during the brewing process so that the remaining spent grains are higher in protein but lower in energy than the original grain. The crude protein, oil and crude fiber content of the spent grains are about twice that of the original grain. The use of brewer's dried grains in starter diets should be less than 10%. Up to 30% can be used in grower diets, although the feed efficiency will be reduced. The restriction is due to the high fiber content of brewer's dried grains (Ademosun, 1973).

Malt Sprouts

Malt sprouts are obtained from malted barley by removal of the rootlets and sprouts. They may also include some of the malt hulls, other parts of the malt, and foreign material. They must contain a minimum of 24% crude protein.

Nutrient content of malt sprouts (Batal and Dale, 2010)

  • Dry matter: 92%
  • Metabolizable energy: 1410 kcal/kg (640 kcal/lb)
  • Crude protein: 25%
    • Methionine: 0.32%
    • Cysteine: 0.23%
    • Lysine: 1.10%
    • Tryptophan: 0.41%
    • Threonine: N/A
  • Crude fat: 1.2%
  • Crude fiber: 15.0%
  • Ash: 7.0%
    • Calcium: 0.20%
    • Total phosphorus: 0.70%
    • Non-phytate phosphorus: none
References and Citations
  • Adams, C. A. 2001. Interactions of feed enzymes and antibiotic growth promoters on broiler performance [Online]. Cahiers Options Méditerranéennes 54: 71–74. Available at: http://ressources.ciheam.org/om/pdf/c54/01600013.pdf(verified 10 July 2013)
  • Ademosun, A. A. 1973. Evaluation of brewer's dried grains in the diets of growing chickens. British Poultry Science 14(5): 463–468. (Available for purchase online at: http://dx.doi.org/10.1080/00071667308416053) (verified 10 July 2013)
  • Ankrah, N. O., G. L. Campbell, R. T. Tyler, B. G. Rossnagel, and S.R.T. Sohansanj. 1999. Hydrothermal and beta-glucanase effects on the nutritional and physical properties of starch in normal and waxy hull-less barley. Animal Feed Science and Technology 81: 205–219. (Available for purchase online at: http://www.animalfeedscience.com/article/PIIS037784019900084X/abstract) (verified 10 July 2013)
  • Bartnick, M., and I. Szafrańska. 1987. Changes in phytate content and phytase activity during germination of some cereals. Journal of Cereal Science 5: 23–28. (Available for purchase online at: http://dx.doi.org/10.1016/S0733-5210(87)80005-X) (verified 10 July 2013)
  • Batal, A., and N. Dale. 2010. Feedstuffs Ingredient Analysis Table: 2011 edition. Feedstuffs.
  • Bennett, C. D., H. L. Classen, K. Schwean, and C. Riddell. 2002. Influence of whole barley and grit on live performance and health of turkey toms. Poultry Science 81: 1850–1855. (Available online at: http://ps.fass.org/content/81/12/1850.short) (verified 11 July 2013)
  • Bennett, C. D., and H. L. Classen. 2003. Performance of two strains of laying hens fed ground and whole barley with and without access to insoluble grit. Poultry Science 82: 147–149. (Available online at: http://ps.fass.org/content/82/1/147.short) (verified 11 July 2013)
  • Biggs, P. and C. M. Parsons. 2009. The effects of whole grains on nutrient digestibilities, growth performance and cecal short-chain fatty acid concentrations in young chicks fed ground corn-soybean meal diets. Poultry Science 88: 1893–1905. (Available online at: http://ps.fass.org/content/88/9/1893.short) (verified 11 July 2013)
  • Brown, B. D. 2003. Rotation factors and field selection. p. 8. In L. D. Robertson and J. C. Stark (eds.) Idaho Spring Barley Production Guide. BUL 742. University of Idaho, College of Agriculture and Life Sciences, Moscow. (Available online at: http://www.cals.uidaho.edu/edcomm/pdf/BUL/BUL0742.pdf) (verified 11 July 2013)
  • Griffey, C., W. Brooks, M. Kurantz, W. Thomason, F. Taylor, D. Obert, R. Moreau, R. Flores, M. Sohn, and K. Hicks. 2010. Grain composition of Virginia winter barley and implications for use in feed, food and biofuels production. Journal of Cereal Science 51: 41–49. (Available for purchase online at: http://dx.doi.org/10.1016/j.jcs.2009.09.004) (verified 11 July 2013)
  • Jeroch, H. and S. Danicke. 1995. Barley in poultry feeding: A review. World's Poultry Science Journal 51:271–291. (Available for purchase online at: http://dx.doi.org/10.1079/WPS19950019) (verified 11 July 2013)
  • Knudsen, K.E.B. 1997. Carbohydrate and lignin content of plant materials used in animal feeding. Animal Feed Science and Technology 67: 319–338. (Available for purchase online at: http://dx.doi.org/10.1016/S0377-8401(97)00009-6) (verified 10 July 2013)
  • Linares, L. B., J. N. Broomhead, E. A. Guaiume, D. R. Ledoux, T. L. Veum, and V. Raboy. 2007. Effects of low phytate barley (Hordeum vulgare L.) on zinc utilization in young broiler chicks. Poultry Science 86:299–308. (Available online at: http://ps.fass.org/content/86/2/299.abstract) (verified 11 July 2013)
  • Salarmoini, M., G. L. Campbell, B. G. Rossnagel, and V. Raboy. 2008. Nutrient retention and growth performance of chicks given low-phytate conventional or hull-less barleys. British Poultry Science 49: 321–328. (Available online at: http://dx.doi.org/10.1080/00071660802136890) (verified 11 July 2013)
  • Shewry, P. R. and A. S. Tatham. 1990. The prolamin storage proteins of cereal seeds: Structure and evolution. Biochemistry Journal 267:1–12. (Available online at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1131235/) (verified 11 July 2013)
  • Tester, R. F., and W. R. Morrison. 1992. Swelling and gelatinization of cereal starches III. Some properties of waxy and normal non-waxy barley starches. Cereal Chemistry 69: 654–658. (Available online at: http://www.aaccnet.org/publications/cc/backissues/1992/Documents/CC1992a158.html) (verified 11 July 2013)
  • Weremko, D., H. Fandrejewski, T. Zebrowska, I.K., J.H. Kim and W.T. Cho. 1997. Bioavailability of phosphorus in feeds of plant origin for pigs - A review. Asian-Australian Journal of Animal Science 10: 551–566. (Available online at: http://www.ajas.info/journal/view.php?number=19220 (verified 11 July 2013)

 

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 8093

Resources for Organic Certification of Research Sites and Facilities

Wed, 05/22/2019 - 09:23

eOrganic author:

Jim Riddle, University of Minnesota

Websites
  • Agricultural Marketing Service - National Organic Program [Online]. Agricultural Marketing Service United States Department of Agriculture. Washington, DC. Available at: http://www.ams.usda.gov/nop (verified 16 March 2010).
  • Midwest Organic and Sustainable Education Service [Online]. Spring Valley, WI. Available at: http://www.mosesorganic.org (verified 16 March 2010).
  • ATTRA - National Sustainable Agriculture Information Service: organic farming, sustainable ag, publications, newsletters [Online]. National Center for Appropriate Technology (NCAT). Fayetteville, AR. Available at: http://www.attra.org (verified 16 March 2010).
  • USDA ERS- Organic Agriculture [Online]. United States Department of Agriculture Economic Research Service. Washington, DC. Available at: http://www.ers.usda.gov/topics/natural-resources-environment/organic-agr... (verified 24 August 2015).
  • Organic Farming Research Foundation -- Home [Online]. Organic Farming Research Foundation. Santa Cruz, CA. Available at: http://ofrf.org/ (verified 16 March 2010).
  • OMRI - Organic Material Review Institute [Online]. Eugene, OR. Available at: http://www.omri.org/ (verified 16 March 2010).
  • Organic Trade Association [Online]. Greenfield, MA. Available at: http://www.ota.com/index.html (verified 17 Dec 2008).
  • New Farm For Farmers | Rodale Institute [Online]. Rodale Institute. Kutztown, PA. Available at: http://www.rodaleinstitute.org/new_farm (verified 16 March 2010).
  • The Organic Center [Online]. Washington DC. Available at: http://www.organic-center.org/ (verified 5 Nov 2015).
  • How to Go Organic - Resource for transitioning to organic [Online]. The Organic Trade Association. Greenfield, MA. Available at: http://www.howtogoorganic.com/ (verified 16 March 2010).
  • Organic Agriculture: Organic Agriculture Home [Online]. Food and Agriculture Organization of the United Nations. Rome, Italy. Available at: http://www.fao.org/organicag/en/ (verified 16 March 2010).

 

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 727

Scouting for Vegetable and Fruit Pests on Organic Farms

Tue, 05/21/2019 - 14:42


Resources Mentioned in the Webinar

Fruit Crop Pest Models - WSU Decision Aid System

Garden Insects of North America - W. Cranshaw

Natural Enemies Handbook - M.L Flint, S. Dreistadt

Northeast Vegetable and Strawberry Pest Identification Guide-University of Massachussetts

North Carolina State University: Insect and Related Pests of Vegetables

Pacific Northwest Insect Management Handbook

Integrated Crop and Pest Management Guidelines for Commercial Vegetable Production. Cornell University

Pests of the Garden and Small Farm, M.L. Flint

Pests of the West - W. Cranshaw

University of California IPM Online: Natural Enemies Gallery

USPEST.ORG IPM Pest and Plant Disease Models and Forecasting

About the Webinar

Crop consultant, Doug O’Brien, and organic farmer, Helen Atthowe, share their pest monitoring and decision making tips and short cuts. Learn how to look for insect, disease, and crop quality problems on organic vegetable and fruit farms. We will also touch on some ideas about how to maintain records that will help you better understand pest problems and what to do about them.

This webinar was funded by Western SARE project SW09-031: Bean Mold Management Tools and Rotational Systems Management.

Handout of the slides from this webinar

About the Presenters

Helen Atthowe has been farming on her own and consulting for other organic vegetable and fruit farms for 25 years. She was a horticulture extension agent for 15 years and owned and operated Biodesign Farm (30 acre diverse organic fruit and vegetable farm) in western Montana for 17 years. She recently spent 6 months as a consulting vegetable grower for a 2000 acre organic vegetable and fruit farm in northern Colorado with a 5000 member CSA.

Doug O'Brien currently owns and operates Doug O’Brien Agricultural Consulting, providing on-site technical advice, field monitoring, and research for clients involved in fresh produce growing, harvesting, cooling and marketing. He is an adjunct professor at Cabrillo College, in Santa Cruz, CA and teaches classes in organic farming. Previously, Doug was a co-owner of an organic produce brokerage company, a crop production manager, and an assistant farm advisor.

Find all upcoming and archived eOrganic webinars at http://www.extension.org/pages/25242 

 

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 8951