USDA Issues Computer Model for Less Nitrogen Use

November 12, 1999

USDA's Agricultural Research Service has released a computer model designed to eliminate uncertainties that lead farmers to over-apply nitrogen as so-called "insurance fertilizer." It could save millions of dollars worldwide in increased crop yields, fewer soil test and less nitrogen use, researchers say.

ARS soil scientist Alan E. Olness, Morris, MN, developed the new model that is available on the Internet http://www.infolink.morris.mn.us/~lwink/products/products.htm.

It uses soil and weather information to predict how much nitrogen will be produced by soil microbes after spring planting. Often that amount can be 50-100 pounds per acre.

Results from a soil test just before planting tell the model how much nitrogen the soil has at that time. The model also requires farmers to know the soil's clay and organic matter content and pH and to provide data from a field weather station. It predicts nitrate-nitrogen content for up to 90 days after planting, well before the critical nitrogen uptake period for corn.

If the rate of natural nitrogen production doesn't meet crop needs, farmers will add nitrogen fertilizer to make up the difference. If nitrogen production is predicted to be too rapid, farmers can slow it down by planting without tillage.