Changing Poultry Manure into a Water-Safe Fertilizer

It’s a case of three wastes making a resource. Wastes from drinking water treatment plants and industrial plants have made poultry litter a safer fertilizer for nearby farms.

Alum in the water treatment residues and iron in certain industrial residues strongly bind the phosphorus in poultry manure. This reduces water-soluble concentrations of phosphorus, making it much less likely to wash into waterways. The water treatment residues also contain liming materials which can make soils less acidic.

Recycled as fertilizer, manure treated with these byproducts can improve poor soils inexpensively and help farmers continue to use poultry litter (a manure and sawdust mixture) as fertilizer. Eton E. Codling, an Agricultural Research Service soil scientist at Beltsville, Md., made the finding in a lab study announced in the current issue of the Journal of Environmental Quality. ARS is the chief scientific research agency for the U.S. Department of Agriculture.

Spurred by toxic outbreaks of the microbe Pfiesteria piscicida in tributaries of the Chesapeake Bay, Maryland is phasing in the country’s strictest limitations on farm use of poultry litter and other phosphorus fertilizers. Phosphorus washed into waterways is thought to be a possible cause of Pfiesteria outbreaks. Farmers with soils measured at the highest levels of water-soluble phosphorus would not be able to apply poultry litter or other phosphorus fertilizer until the levels subsided.

In his lab study, Codling used soils and poultry litter from three such farms--all long- established poultry farms--along with byproducts from Chesapeake Bay area facilities. He plans to test the litter-byproduct mixtures in corn and soybean fields on these farms.

Scientific contact: Eton E. Codling, ARS Environmental Quality Laboratory, Beltsville, Md., phone (301) 504-5708, fax (301) 504-5048, codlinge@ba.ars.usda.gov.