Synthetic Nitrogen Fertilizers
Nitrogen is abundant in our atmosphere but rare in the soil – it is naturally “fixed” (converted to soil availability) by bacteria on the roots of leguminous plants, or by a strike of lightning. The Haber-Bosch process was developed in the early 20th century to combine nitrogen from the air with hydrogen at high temperature and pressure to make anhydrous ammonia (NH3), the basis for all synthetic nitrogen fertilizers as well as munitions used in warfare. The hydrogen source for the process is natural gas, a non-renewable resource that currently accounts for 80 to 90 percent of the cost of fertilizer production. In the conventional system, our very ability to feed ourselves is dependent upon a non-renewable fossil fuel.
Synthetic nitrogen fertilizer became popular in the U.S. after World War II when large stocks of leftover ammonium nitrate munitions were marketed for agricultural use. However, the widespread adoption of synthetic fertilizer and associated agricultural practices had a host of unintended consequences to our environment, the quality of our foods, and the sustainability of our food system.
Synthetic fertilizers are banned from USDA’s organic production standards, but are used in conventional food production on a massive scale. Over 13 million tons of synthetic nitrogen were spread over American farmland in 2008 alone, covering about one-eighth of the continental land mass.1
Synthetic N Pollutes
- A relatively small amount of the nitrogen contained in fertilizers applied to the soil is actually absorbed by plants. The rest runs off into waterways, where it creates massive "algal blooms." The overgrown nitrate-fed algae starve water of oxygen, suffocating fish and other aquatic life and creating huge “dead zones” in lakes and oceans. The number of identified oceanic dead zones has grown from 60 in 1995 to 405 in 2008.2 The Mississippi River fertilizes a dead zone in the Gulf of Mexico that fluctuates in size from 3,000 to 8,000 square miles.3
- Runoff nitrogen also leaches into groundwater, contaminating drinking water and creating widespread health hazards.
- Soil bacteria convert excess nitrates into nitrite ions, which, if ingested, get into the bloodstream where they attach to hemoglobin molecules, reducing their ability to carry oxygen and starving the body of oxygen. Nitrates in drinking water used for infant formula can cause potentially fatal blue-baby syndrome, and can cause serious health problems for adults and children alike. High levels of nitrates and nitrites were found in 25,000 community wells that provided drinking water to two thirds of the nation's population.
- Excess nitrates in the soil sometimes convert to nitrosamines, which have been shown to cause tumors in laboratory animals. Nitrate-contaminated water is also linked to reproductive problems, urinary and kidney disorders, and bladder and ovarian cancer.
- Applying fertilizer releases oxidized nitrates, which contribute to the formation of smog, act as greenhouse gases, and destroy protective ozone. Nitrogen oxides also react with water in the atmosphere to form acid rain.
Synthetic N Requires a Nonrenewable Energy Source
- Synthetic fertilizers use non-renewable fossil fuels. The energy consumed to make synthetic nitrogen for U.S. farmers for one year (13.1 million tons) would heat about 5.5 million Midwestern homes all year long.
- A study of Rodale Institute’s Farming Systems Trial from 1981 to 2002 shows that energy inputs for organic corn production were about 30% lower than for conventionally produced corn.5
- Since 80-90% of the cost of Synthetic N production comes from natural gas, synthetics-based conventional ag is vulnerable to fluctuating fuel prices. A change in the price of natural gas of $1 per million BTU results in about a $33 per ton change in ammonia production cost.
- Twelve years ago, the U.S. was the world's largest exporter of N fertilizer; now we are the largest importer. More than half the nitrogen our farmers now use comes from places like Trinidad, Russia, and the Persian Gulf, where natural gas is cheaper than in the U.S.4
Synthetic N Makes Weak Soil and Weaker Plants
- Synthetic fertilization does not build up soil organic matter.
- Since heavy use of synthetic fertilizers began in the 1940s, 4.7 billion acres of soil have been significantly degraded worldwide. Low soil fertility and high rates of erosion lead to poor crop yields, land abandonment, and deforestation.6
- Plants fed with synthetic fertilizers in poor soils have weak root systems, making them vulnerable to drought and disease, requiring increased irrigation and application of pesticides.
- Over time, synthetically fertilized soil deteriorates and compacts, losing its spongy, absorptive qualities. This leads to erosion and promotes rapid runoff. Instead of slowly absorbing into the soil and plant roots, water runs across “hardpan” soil and away, carrying more inputs into waterways in turn.
- Thus, synthetic fertilizers degrade land and water and create an increasing cycle of dependence.
- Degraded soil lacks trace nutrients that make a food nutritious.
The Organic Valley Difference
Organic Valley farmers support soil fertility in ways that are inherently better for soil, air, and water quality. Going above and beyond the USDA’s organic standards, our methods include using natural compost, planting cover crops (helper crops which pull atmospheric nitrogen into the soil), rotating crops (which gives the land a break to rebuild soil quality naturally), and pasturing animals. Our use of buffer strips, composting of manure, and reduction of inputs means there is less likelihood of contamination issues due to run-off, and soil erosion is significantly reduced. In addition, since organic farms have higher levels of organic matter in the soil, water is more likely to be absorbed and retained. Organic Valley farmers take care of the soil, because healthy plants are built "from the ground up!”
Long-term research at Rodale Institute shows that properly managed cover crops (legumes, grains, grasses or mixtures) can provide all the nitrogen crops need.7
- This organic regenerative approach builds new soil organic matter, creating a healthy and resilient soil.
- Biologically alive soil provides more structure, preventing erosion.
- Healthy soil has more permeability and aeration for healthier microorganism growth.
- More nutrients are available in organically managed soil that are vital for healthy plant growth, productivity, and drought and disease tolerance.
- Building soil organic matter sequesters carbon dioxide from the atmosphere, reducing greenhouse gases.
- Allen, Will, cited in “Will Allen: We Need Food and Farming Regulation NOW!”www.chelseagreen.com/content/will-allen-we-need-food-and-farming-regulation-now/
- Rich, Deborah K., "The case against synthetic fertilizers," San Francisco Chronicle, 1/14/06 www.sfgate.com Accessed 5/19/09.
- Obreza, Parsons, and Morgan; Nitrogen Fertilizer Sources: What does the future hold for citrus producers? fact sheet, Soil and Water Science Department, Florida CES, Institute of Food and Agricultural Sciences, U.Fla. pub February, 2006. Revised February, 2009. http://edis.ifas.ufl.edu/SS457
- Pimentel, D., 2006. Impacts of organic farming on efficiency and energy use in agriculture. www.organicvalley.coop/fileadmin/pdf/ENERGY_SSR.pdf.
- Pimentel, D., Hepperly, P., Hanson, J., Douds, D., and R. Seidel. 2005. Environmental, energetic, and economic comparisons of Organic and Conventional farming systems. Bioscience 55(7):573-582.
- IAASTD, 2008. International Assessment of Agricultural Knowledge, Science and Technology for Development Global Report.
- LaSalle, Hepperly, and Diop, "The Organic Green Revolution" Rodale, 2008, www.rodaleinstitute.org/files/GreenRevUP.pdf