Keeping yields, profits and water quality high

Researchers investigate the potential of low-input farming systems to benefit both farmers and the environment

One of the key questions facing agriculturalists in the 21st century is how to produce adequate amounts of food and farm income while protecting environmental quality. Diversified, low-external-input (LEI) farming systems offer one possible approach for maintaining adequate productivity and profitability while reducing pollution by agrichemicals and still improving water quality. LEI systems rely heavily on ecological processes for soil fertility and pest management, but can include some use of synthetic fertilizers and pesticides.

A team of investigators based at Iowa State University conducted a multiyear field experiment in Boone County, IA, to determine whether the yield, weed suppression, and profit characteristics of LEI systems can match or exceed those of a conventional system. Results from the study were published in the May-June 2008 issue of Agronomy Journal.

The experiment included a two-year, corn-soybean rotation, a three-year corn-soybean-small grain-red clover rotation, and a four-year corn-soybean-small grain-alfalfa-alfalfa rotation. Conventional rates of synthetic fertilizers were applied in the two-year rotation, whereas composted cattle manure and reduced rates of synthetic fertilizers were applied in the three- and four-year rotations. Weed management in the two-year rotation was based on conventional rates of herbicides, whereas in the three- and four-year systems, herbicides were applied in bands in corn and soybean, greater reliance was placed on cultivation, and no herbicides were applied in small grain and forage legume crops.