MADISON, WI, May 3, 2010-Conventional agriculture production relies heavily on fossil fuels, particularly in its ability to provide energy at a low cost. However, the uncertain future of fossil fuel availability and prices point to need to explore energy efficiencies in other cropping systems.
Most of the U.S. Corn Belt relies on a two-year rotation of corn and soybean with heavy inputs of fertilizer, herbicides and pesticides derived from fossil fuels to achieve high yields keep costs low. Matt Liebman, Michael Cruse, and their colleagues at Iowa State University conducted a six-year study to compare energy use of a conventionally managed corn and soybean system with two low input cropping systems that use more diverse crops and manure applications, but also use less fertilizer and herbicides. The results were published in the May/June 2010 edition of Agronomy Journal, published by the American Society of Agronomy.
The two input systems consisted of a three-year rotation of corn-soybean/small grain/red clover and a four-year rotation of corn-soybean-small grain/alfalfa-alfalfa. Between 2003 and 2008, nitrogen fertilizer inputs in the 3-year rotation decreased 66% and decreased 78% in the 4-year rotation. Herbicide use decreased 80% in the three-year rotation and 85% in the four-year rotation. Despite the energy input reduction, corn and soybean yields matched or exceeded the conventional system yields.
Did the application of manure decrease the fossil fuel energy costs? Manure prices are dependent on local economic conditions, but the two low-input systems used 23% to 56% less fossil energy than conventional systems. To analyze the energy and economic costs of manure application, the researchers used two approaches. One where manure was a waste product of live stock and essentially free of cost except for the energy used in its application, and a second approach as if the costs of manure were the same as commercial fertil
|Contact: Sara Uttech|
American Society of Agronomy