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New Model Saves Farmers Costs of Fertilizer, Soil Tests

By Don Comis
November 10, 1999

A new computer model from the Agricultural Research Service could save farmers worldwide millions of dollars in increased crop yields, fewer soil tests and less use of nitrogen fertilizer.

The Nitrogen Fertilizer Decision Aid is available on the World Wide Web. It eliminates uncertainties that lead many farmers to over apply nitrogen as so-called “insurance fertilizer.”

ARS soil scientist Alan E. Olness in Morris, Minn., developed the new model. 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 to 100 pounds per acre.

Results from a soil test just before planting tell the model how much nitrogen the soil has at that time. In addition, the model requires farmers to know the soil's clay and organic matter content and pH and to provide data from a field weather station.

The model 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 their crop needs, farmers will add nitrogen fertilizer to make up the difference. If production of nitrogen is predicted to be too rapid, farmers can slow it down by planting without tillage.

The model can be downloaded from:

ARS is the chief research agency of the U.S. Department of Agriculture.

Scientific contact: Alan E. Olness, ARS North Central Soil Conservation Research Laboratory, 803 Iowa Ave., Morris, MN 56267; phone (320) 589-3411, Ext. 100, fax (320) 589-3787,