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  You are here:  PublicationsMaine Organic Farmer & GardenerFall 2007Cottonseed as Fertilizer   
 Cottonseed Meal for Fertilizer? Minimize

Far Better Options Exist

by Alex Owre

High-nitrogen content (6-2-2) cottonseed meal has long been employed as an organic fertilizer that lowers the pH of soil, poses little danger of burning plants, and provides nitrogen, phosphorus and potassium as well as many minor plant food elements. It is cheap and readily available.

In some states, however, cottonseed meal is not allowed in a certified organic operation, and it does not appear as a recommended soil amendment in MOFGA’s Fact Sheet Number 11, “Natural Sources of Plant Nutrients.” (See www.mofga.org/Publications/FactSheets)

Eric Sideman, Ph.D., MOFGA’s organic crop specialist and author of the fact sheet, says the omission is due to two restrictions on using cottonseed meal in the USDA’s National Organic Program (NOP) standards. The first restriction requires that cottonseed meal be pesticide free, which, says Sideman, though possible, is difficult to demonstrate. Though cotton is a heavily sprayed crop, conventionally grown, pesticide-free meal is available on the market.  

The International Certification Standard set by the Organic Crop Improvement Association places cottonseed meal in the Restricted category, maintaining that it may contain substantial pesticide residues and recommending its use only if documented to be residue-free. Otherwise, cottonseed meal MUST be composted before use to break down toxic residues. (Cotton gin trash, containing seed hulls, is recognized as potentially more contaminated than the seed meal, because many residues are in the hull.)

The conventional U.S. cotton industry says that “if there is any trace of residue [on cottonseed meal] it is minuscule and far below levels to harm anyone  … Essentially the only crop protection products used on cotton are used before boll opening. Only harvest aid products are applied after boll opening and these products are contact leaf defoliants, not systemic. In addition, cotton fiber and cottonseed hulls would cover and protect the cottonseed meal from any crop protection product exposure.”  

Note that this statement would not be true for genetically engineered cotton, which expresses the gene for the Bacillus thuringiensis bacterial toxin in all plant parts. Thus, the second NOP restriction cited by Sideman:  that cottonseed be demonstrated to be free of genetically engineered material. As with other crops, this is exceedingly difficult unless the material comes from organic crops.

Otherwise, Sideman recommends cottonseed as a fertilizer the same as he does for soybean meal, which has an analysis of about 6-1-1. He notes, however, that soybeans by comparison pose little pesticide risk, and soy is not genetically engineered to contain a toxin in all of its cells, as cotton is.  Soy is engineered to resist the herbicide Roundup by altering a gene in the plant, not be adding genes. MOFGA currently allows soybean meal from any source as a soil amendment.

Rather than rely on an “imported” product to provide fertility to the farm or garden, MOFGA generally recommends farm-generated fertility or, at least, recycling fertility within a community. This makes economic as well as environmental sense.  A 4-pound bag of cottonseed meal costs just a little under $6, so you’d be paying $6 for 0.24 pounds of nitrogen, or about $25 per pound of nitrogen.  (For comparison, alfalfa meal costs about $46 per pound of N; blood meal, $12;  soybean meal, $17.  These prices are based on small quantities, such as 5-pound bags.)  

Four pounds of hairy vetch seed (for a nitrogen-fixing green manure crop), on the other hand, will cost about $13 and can fix over 100 pounds of N per acre – for a cost of 13 cents per pounds of N; and growing your own nitrogen adds lots of organic matter to the soil as well; protects the soil from erosion; helps keep existing nutrients from leaching; has less environmental impact than buying N from any off-farm source; and supports a diverse ecology in the garden.

Likewise, compost, leaves and grass clippings can supply all of the fertility needed in a garden and may be free – and collecting them can even save you from paying for a membership at a gym.


    

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