Computer helps spread manure.

A computer program developed at Purdue University, West Lafayette, Ind., is helping farmers use manure as a more efficient fertilizer. The program, called AMANURE, "determines storage volumes, application rates, acres needed for application, and if supplemental fertilizer is needed for specific crops," notes Don Jones, an agricultural engineer at the university.

For centuries, some farmers have used manure as a fertilizer, but many others treated it as a liability, a waste product to be disposed of. Gary Eller, who set up a custom sludge applicator's business on his family's farm near Kokomo, Ind., points out that "Even those who used manure as a fertilizer had to guess at its nutrient value by hit-and-miss methods." He uses the computer program to show farmers the value of their livestock manure and to help avoid potential environmental hazards from nutrient runoff.

Alan Sutton, a Purdue animal scientist, explains, "Today, environmental concerns and tight profit margins have forced livestock producers to re-evaluate their manure handling plans. Proper storage and applications on modern commercial farms are compatible with proper pollution control methods."

About 75% of the nitrogen, phosphorus, and potassium fed...