Conventional Vs. Organic Nitrogen in Agriculture
Nitrogen is one of the main sources of plant nutrition. Billions of dollars are spent annually in the U.S. alone to provide nitrogen to crops. Concerns about health, expense and the environmental impact of agricultural uses of nitrogen are inspiring the demand for organic fertilizing practices.
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Sources of Agricultural Nitrogen
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Conventional nitrogen is primarily derived from using tremendous amounts of heat and pressure to convert atmospheric nitrogen into a form that plants can use. Other major sources come from processed ammonia. In organic agriculture, compost, compost tea (made by soaking compost in water, then straining out the large particles) and fish emulsion are used to fertilize crops. Many farms also over-crop with legumes because these types of plants work symbiotically with a bacteria that fixes atmospheric nitrogen for that plant. When the legume is chopped back or dies, it sheds its roots and releases the nitrogen into the soil.
Use & Expense
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The prices for agricultural nitrogen fertilizer products ranged from $300 and $500 per ton in 2010, according to the USDA. The USDA figures for the 2007 nitrogen fertilizer consumption in the U.S. is over 22 million material tons, and rising annually. Compost consumed in the U.S. averaged about 83 thousand material tons between 2000 and 2007. Costs of compost generated on-site consist of the labor to maintain it and spread it over the fields. Offsite costs of compost depend on how far it is delivered. Costs of inter-planting legumes consists of the initial cost of inoculated seed, and then labor to "chop and drop."
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Carbon Footprint
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Manufactured nitrogen fertilizers is produced with carbon-based energy. Their carbon footprint includes oil production (in the US and abroad), shipping the oil, building and maintain the fertilizer factory and shipping the fertilizers to the farmer. The footprint is everlasting because farmers must re-apply fertilizers every season. If an organic farm produces fish emulsion or compost entirely on site, the carbon footprint is minimal. Michael Pollan, author of "The Omnivore's Dilemma," points out that large organic farms often ship their compost in from remote sites. In permaculture, nitrogen-fixing legumes are found locally, or a small amount of inoculated seeds is shipped only once. The carbon footprint ends here because the legumes reseed and all compost is produced onsite.
Environmental Degradation/Renewability
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The energy used to transform atmospheric nitrogen into fertilizer is immense and is provided by non-renewable fossil fuels. The pollution produced from manufacture, as well as the run-off and seepage on the farm degrades the environment. Compost and fish emulsion, on the other hand, are renewable and do not degrade the environment when produced on the farm. Using legumes to fix atmospheric nitrogen in combination with composting produces the most sustainable, environmentally positive nitrogen for agriculture. In a permaculture setting, the environment is enriched and diversified instead of degraded.
Health Impact
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In 2003, researchers at the University of California-Davis published the results of a trial conducted on the healthfulness of food produced organically and conventionally. What they found was that food produced from chemical fertilizers using the conventional method were lower in vitamins, antioxidants and antimicrobials. According to the EPA, high concentrations of nitrogen fertilizer runoff into drinking water sources can cause a fatal illness in children, called blue baby syndrome. Poorly managed composting also produces harmful runoff that can seep into water reserves. Integrated legume planting does not produce significant runoff because the surrounding plants readily absorb the low, steady supply of nitrogen.
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References
- Photo Credit agriculture image by Gudellaphoto from Fotolia.com
