Development of a New Manure Amendment for Reducing Phosphorus Runoff and Ammonia Volatilization from Poultry Litter.

The addition of aluminum sulfate (alum) to animal manures has been shown to greatly reduce both phosphorus (P) runoff and ammonia (NH₃) emissions.  Resulting improvements in poultry production, lower energy costs and environmental benefits from alum have resulted in widespread use by the poultry industry. Over one billion broiler chickens are grown with alum in the USA each year.  However, the price of alum has increased significantly, creating a need for cheaper products that control P runoff and NH₃ emissions. The objective of this research was to develop an inexpensive manure amendment that is as effective as alum in reducing P runoff and NH₃ volatilization from poultry litter. Sixteen manure amendments were created using different ratios of alum mud, bauxite ore, sulfuric acid, liquid alum and water.  Alum mud is a waste product that is produced during the manufacture of alum when made by mixing sulfuric acid with bauxite. A laboratory NH₃ volatilization study was conducted using 11 treatments; untreated poultry litter, litter treated with dry or liquid alum and litter treated with eight of the new mixtures. All of the manure amendments resulted in significantly lower NH₃ losses than the controls. Ammonia volatilization with dry and liquid alum was reduced by 86% and 75%, respectively.  Ammonia losses with the eight new amendments ranged from 62 to 73% less than controls and were not significantly different from liquid alum and the three most effective mixtures were not significantly different from dry alum. All of the treatments also significantly reduced water extractable P (WEP); three of which resulted in significantly lower WEP than with dry alum. The most promising new products were mixtures of alum mud, bauxite, and sulfuric acid. The potential impact of these new amendments could be enormous, since they could be produced for less than half the price of alum, while being equally effective at reducing both P runoff and NH₃ emissions.