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Photo: Phosphorus recovered from poultry litter
Phosphorus from poultry litter can be used as a fertilizer, and the litter can then be recycled as bedding material or used for bioenergy conversion. Photo courtesy of Matias Vanotti, ARS.

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Mining Manure for Phosphorus

By Ann Perry
February 29, 2008

Underground phosphorus deposits around the world are mined for use as a much-valued fertilizer. Now Agricultural Research Service (ARS) soil scientists Ariel Szogi, Matias Vanotti and Patrick Hunt have found a way to “mine” the phosphorus in poultry manure.

In 2006, the United States produced 8.9 billion broilers—and piles and piles of residual litter rich in phosphorus and nitrogen. Although poultry litter is typically used by farmers to fertilize their field crops with these two nutrients, it usually contains more phosphorus than the crops need. The excess phosphorus has the potential to wash away and pollute nearby rivers and lakes.

Szogi, Vanotti and Hunt have developed a method to obtain the phosphorus in poultry litter—consisting of a rapid removal and recovery of phosphorus in solid form—which they’ve dubbed “Quick Wash.” ARS has applied for a patent on this process.

The process selectively removes up to 80 percent of the phosphorus from poultry litter while leaving the nitrogen. The washed poultry litter can be safely applied to farm fields as a balanced fertilizer or used again as a bedding material. It can also serve as a feedstock for bioenergy production.

U.S. farmers use some 3.7 billion pounds of phosphorus in annual crop production. But poultry and other livestock produce about 1 billion pounds more phosphorus than livestock producers can use.

This innovation provides an environmentally sound phosphorus recovery system that livestock producers can use to manage the excess phosphorus in manure. Poultry producers also benefit by producing a concentrated phosphorus product that can be moved easily off farms and reused as fertilizer.

ARS is interested in finding business partners to move the product to market.

Szogi, Vanotti and Hunt work at the ARS Coastal Plains Soil, Water and Plant Research Center in Florence, S.C. ARS is the U.S. Department of Agriculture's chief scientific research agency.