Buying and Sourcing Cover Crop Seed for Organic Farming Systems

Things to Consider When Purchasing Cover Crop Seed

Sources

Demand for cover crop seed is greater than ever. Organic producers who desire to reduce production costs and conserve natural resources are increasingly turning to cover crops as a method to accomplish those goals. This demand has encouraged research and breeding efforts on cover crop species. Seed sold in the U.S. is produced domestically as well as abroad. Winter annual cover crops including legumes and cereal grains are produced mostly in the northeast and in Canada. Many tropical summer legumes are produced in Hawaii, and some varieties of tropical legumes may come from Asia, India, and South America.

Figure 1. Oat 'Saia' cover crop. Photo credit: Mikio Miyazoe, Oregon State University.

Organic cover crop seed

The National Organic Program regulations on annual seeds, including cover crop seeds, state that organically grown seeds must be used, when commercially available (CFR 205.204). If a grower can demostrate to the certifying agent that organic seed was not available, conventionally-grown, untreated seed can be used. Many commercially available cover crop seeds have been treated with prohibited substances such as a synthetic fungicide, but in many cases untreated seed is available. Fungicide- or insecticide-treated seeds may not be used by organic producers.

Nonorganic, untreated seeds can be used as a last resort in the following situations:

• When an equivalent organically-produced variety is not available, untreated seeds may be used.
• When a temporary variance has been granted by the producer’s certification agency, if approved by the USDA in response to a natural disaster or for research purposes.

Treated seeds can be used in the following situations:

• When the seed treatment is allowed by the NOP (such as certain seed pelleting materials for small seeded crops).
• When Federal or State phytosanitary regulations require that seed be treated with a prohibited substance (such as a synthetic pesticide).

Producers who plant nonorganic untreated seed must provide documentation to support why organic seeds were not planted. Documentation typically includes a written account of at least three attempts (phone calls, written requests) for organic cover crop seed to support a substitution. Treated seed use must be supported by documented evidence of that use of the treatment was required under Federal or State phytosanitary regulations. Organic producers are required to save all seed labels for their records. As always, producers must get approval from their certification agency before making any changes or substitutions to their organic system plan (farm plan). Contact information of some seed suppliers that provide organic cover crop seed are identified in Table 2. For more information, see Sourcing Certified Organic Seed and the National Organic Program Regulations.

GMO-free cover crop seed

Organic producers are prohibited from planting seeds and planting stock grown using "excluded methods." The NOP defines "excluded methods" as, "A variety of methods used to genetically modify organisms or influence their growth and development by means that are not possible under natural conditions or processes and are not considered compatible with organic production. Such methods include cell fusion, microencapsulation and macroencapsulation, and recombinant DNA technology (including gene deletion, gene doubling, introducing a foreign gene, and changing the positions of genes when achieved by recombinant DNA technology). Such methods do not include the use of traditional breeding, conjugation, fermentation, hybridization, in vitro fertilization, or tissue culture."

Some retailers offer seed with claims that it is free of genetic material created by genetic engineering biotechnologies. The claim typically reads “GMO-free,” meaning seeds are free from genetically-modified organisms (GMOs). Laboratory tests can detect genetically modified seed. If producers desire to have GMO-free seed, they should contact the retailer and request documentation for the claim. Several federal agencies are involved in the regulation and oversight of GMO seed and other agricultural products. Product claims of GMO-free are not regulated by the federal government.

Cost

There are many advantages to planting cover crops, such as reduced erosion, enhancement of biological control, and nutrient cycling. There may also be disadvantages, including additional production costs, delays in planting vegetables, increased pest occurrence and nitrogen immobilization. Most of these disadvantages can be avoided with a little research, good planning, and sound execution.

Cover crop costs and benefits should be evaluated based on the degree to which the cover crops fulfill agroecosystem services and production objectives. The complexity of cropping systems that include cover crops can make it extremely difficult to assign a dollar figure to the benefits, particularly those that are achieved in the long term. In one recent analysis of cover crop benefits and costs, cereal cover crops as a group were best suited to increase soil organic matter; legumes were best suited to provide nitrogen, while brassicas were most effective at controlling a wide spectrum of soil pests (Snapp et al., 2005).

The cost of seed will be influenced by the country of origin and the distance it must travel to get to your address. The cost per pound of cover crop seed is most often very reasonable for the ecological services cover crops provide (Snapp et al., 2005). A pound of winter annual rye typically costs between 75 cents to $2.00 a pound. When seeded to 50 pounds an acre, the cost ranges from $38 to $100 per acre.

Legume inoculants

When purchasing legume seeds, it is important to also purchase the correct inoculant. Inoculation is the application of specific nitrogen-fixing bacteria to the seeds before planting. Inoculation is allowed for organic production, so long as the inoculant is not genetically engineered.

The cross-inoculation groups of most of the field and forage legumes commonly grown are tabulated in the University of Florida IFAS Extension publication Nitrogen Fixation and Inoculation of Forage Legumes by Adjei et al. (2006). These nitrogen-fixing bacteria attach to roots of legumes and convert nitrogen gas from our atmosphere to a form of nitrogen that the legume can use. A summary of recommended inoculants for legumes is provided in Table 1. Inoculants are an inexpensive way to ensure a good stand and improve the efficiency of nitrogen fixation. They can be mixed in dry with cover crop seed before planting, but research indicates an improvement in nitrogen fixation is attained when a sticking agent is used (Clark, 2007). A mixture of 10% sugar syrup and water can be added to the cover crop seed prior to adding inoculant for improved contact and retention. The inoculant contains live organisms; therefore, do not expose inoculant to direct sun or excessive heat. Store inoculant in the refrigerator and use before the expiration date. Contact information for inoculant retailers is provided in Table 2.

Seed availability

Popular cover crops such as sorghum-sudangrass and cowpea have many named varieties and are widely available at local feed and seed stores and national seed retailers such as Johnny’s Seeds. Frequently, seeds of these varieties are treated with a fungicide to prevent seed-born diseases, but vendors are often very accommodating and with advance notice they will work with suppliers to reserve seed prior to treatment. Certified organic cover crop seed is becoming increasingly available, but demand is greater than supply and therefore seed can be expensive.

Cover crops with emerging popularity such as velvetbean and sunn hemp can be difficult to locate in large amounts. Many cover crops are sold as unnamed cultivars and are available from a limited number of sources. National retailers specializing in open pollinated seed are a good source for unnamed cultivars. Awareness of the diversity of cover crops has been facilitated by research efforts at universities and by innovative producers. However, cover crop breeding efforts at universities and private industries are sporadic. Perhaps, if demand for cover crops increases, there will be increased motivation to invest in research and development for crop improvement.

Sources of Cover Crops

For small farmers, a number of seed saving and exchange organizations can facilitate the search for specialty seed. In addition to the retailers listed in Table 2, there are a number of additional organizations (many are not-for-profit) that will provide certified organic seed, including  Educational Concerns for Hunger Organization (ECHO), and Seed Savers Exchange. Additional resources include local seed and feed retailers, local Natural Resources Conservation Service (NRCS) offices, and area farmers.

Summary

In summary, integration of cover crops in a cropping system can have significant ecological impacts on the cropping system including crop establishment, nutrient availability, biodiversity enhancement, and pest occurrence. Producers have many options in cover crop species selection and management, and objectives will be dictated by producer needs and production constraints. Cover crop management does require some pre-planning, but the contributions to the farming system can be very beneficial. A plan for planting, mowing and termination are needed to avoid delays and costly errors. If you decide to try something new, be sure to ask about seed size and shape to determine if the seed is appropriate for the planting equipment on your farm. Experiment with a few well-selected species in an area large enough to accommodate the equipment you plan to use before implementing cover crops on the whole farm, if you are new to cover crops.

Organic Seed Databases

• Organic Seed Finder, from the Association of Official Seed Certifying Agencies (AOSCA) and the Organic Seed Alliance
• Directory of Organic Seed Suppliers from ATTRA
• pickacarrot.com Pick A Carrot search engine

References and Citations

• Abdul-Baki, A. A., H. H. Bryan, G. M. Zinati, W. Klassen, M. Codallo, and N. Heckert. 2001. Biomass yield and flower production in sunn hemp: Effect of cutting the main stem. Journal of Vegetable Crop Production 71:83–104.
• Adjei, M. B., K. H. Quesenberry, and C. G. Chambliss. 2006. Nitrogen fixation and inoculation of forage legumes. AG152. Institute of Food and Agricultural Sciences, University of Florida, Gainesville. (Available online at: http://edis.ifas.ufl.edu/AG152) (verified 3 Dec 2008).
• Agricultural Marketing Service—National Organic Program [Online]. United States Department of Agriculture. Available at: http://www.ams.usda.gov/nop/ (verified 8 Dec 2008).
• CFR Section 7, Part 205.204, National organic program regulatory text [Online]. Electronic Code of Federal Regulations. National Archives and Records Administration. Available at: http://www.ecfr.gov/cgi-bin/text-idx?SID=a6a0935ddf00e166695f4c2138bd58d... (verified 15 Jan 2009).
• Clark, A. (ed.) 2007. Managing cover crops profitably. 3rd ed. Sustainable Agriculture Network (now SARE Outreach), Beltsville, MD. (Available online at: http://www.sare.org/publications/covercrops/covercrops.pdf) (verified 11 Dec 2008).
• Piper, C. V., and W. J. Morse. 1928. The velvet bean. Farmers’ bulletin No. 1276. U. S. Department of Agriculture, Washington, DC.
• Snapp, S. S., S. M. Swinton, R. Labarta, D. Mutch, J. R. Black, R. Leep, J. Nyiraneza, and K. O’Neil. 2005. Evaluating cover crops for benefits, costs and performance within cropping system niches. Agronomy Journal 97:322–332.

Further Reading

• Educational Concerns for Hunger Organization [Online]. Available at: http://www.echonet.org (verified 18 Jan 2009).
• Seed Savers Exchange [Online]. Available at: http://www.seedsavers.org (verified 18 Jan 2009).