Annual Phosphorus Applications Unnecessary

WASHINGTON - Jan 26/04 - SNS -- USDA researchers say annual applications of phosphorus fertilizer are unnecessary to maintain profitable yields of wheat, barley, corn and other crops.

ARS soil scientist Ardell D. Halvorson, of the agency's Soil, Plant and Nutrient Research Laboratory in Fort Collins, Colo., conducted several long-term experiments in the Great Plains on farm fields in Montana, Colorado and Nebraska.

In Montana, he found that a single application of phosphorus increased soil test levels and crop yields for more than 17 years. His research in Nebraska and Colorado also showed that farmers can expect improved yields for several years after a single phosphorus treatment.

Since phosphorus is expensive, many farmers tend to use less than the ideal amount each year. Through his research, Halvorson has found economic returns to be greater when applying the correct amount of phosphorus the first year, to eliminate phosphorus deficiency, and then skipping two or three years. Initial cost will be higher, but farmers are likely to have greater profits in the long term.

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