Soy and Soil Pollutants
by Dawn Walls-Thumma - eHow Contributor
In 2009, 77.5 million acres -- more than 3 percent of the United State's land area -- was used for growing soybeans, according to the U.S. Department of Agriculture, making it the United States' second largest crop. Soybeans form many ingredients used in processed food and feed farm animals. Unfortunately, such large-scale production can also result in large-scale pollution of the soil where the soy grows.
Large-scale agriculture typically involves the indiscriminate application of chemical fertilizers, which provide the crops with the nutrients they need to grow. Although soy produces its own nitrogen, it does require phosphorus fertilizer, and the website The Gazette reports that 12 percent of phosphorus applications in Iowa -- the top-producing state for soy -- goes onto soy crops. Excessive nutrients pollute the soil, where they become subject to leaching into groundwater or running off into surface waters.
From Land to Sea
Soil pollution on a single plot of land becomes most harmful when that soil erodes, carrying pollutants into nearby waterways. Phosphorus fertilizers used on soy, in particular, pollute surface waters, causing a process called eutrophication. Eutrophication causes spikes in nutrient levels in surface waters, which encourages the growth of invasive algae, lowering oxygen levels in the water and excluding other aquatic plant and animal species, according to a web page on the website for the Food and Agricultural Organization of the United Nations. In the United States, fertilizer runoff from Midwestern states -- home of the five top soybean states -- annually creates a dead zone in the Gulf of Mexico roughly the size of New Jersey, according to a web page on the website for Carleton College in Minnesota.
Traditional agriculture used crop rotation, cover crops, manures and other methods to build a healthy soil over time. Reliance on chemical fertilizers, on the other hand, does not contribute organic materials to the soil, causing these resources to deplete over time. Instead, large-scale production of soybeans requires chemical fertilizer for the plants to survive. Without these inputs, the soil would become inhospitable to plant life, according to the book "Understanding Environmental Pollution."
Growing only soybeans across acres and acres of land creates a veritable all-you-can-eat buffet for pests that attack soybeans. As a result, intensive soybean production requires the use of pesticides, which contaminate the soil, sometimes remaining in place for decades. In other instances, such as with fertilizers, pesticides leach from the soil into groundwater, where they pose a risk to humans using that water, or runoff into surface waters, where they threaten the health of wildlife.
The application of potentially harmful chemicals requires careful, conscientious use. Testing soils reduces the application of unneeded fertilizer. Agricultural methods that focus on the health of the entire system, especially the soils, require fewer chemical inputs to maintain good crop yields. Christos Vasilikiotis of the University of California-Berkeley reports several studies showing that crops produced using such methods, including soybeans, show improved health and, over time, higher yields than conventionally produced crops.
References, Resources and Credits
- U.S. Department of Agriculture: U.S. Soybean Industry -- Background Information and Statistics
- Friends of the Earth International: The Only Responsible Soy Is Less Soy
- The Gazette: Almost All Fertilizer Pollution Starts on Farms, Study Shows
- Food and Agriculture Organization of the United Nations: Fertilizers as Water Pollutants
- Carleton College Microbial Life Educational Resources: The Gulf of Mexico Dead Zone
- "Understanding Environmental Pollution"; Marquita K. Hill; 2010
- University of California Berkeley: Can Organic Farming Feed the World?
- Photo Credit red algae image by antoine perroud from Fotolia.com
Dawn Walls-Thumma, eHow Contributor