Reducing Nonpoint Source Phosphorus Runoff from Poultry Manure with Aluminum Sulfate

Abstract

Phosphorus (P) is generally considered to be the limiting nutrient for eutrophication in lakes and rivers. Phosphorus runoff from soils fertilized with animal manures, such as poultry manure, can be relatively high even when moderate application rates are used. Recent research has indicated that treating poultry manure with aluminum sulfate (alum) can reduce phosphorus runoff and decrease ammonia volatilization. The objectives of this study were to evaluate the effects of alum applications to poultry manure on (1) ammonia volatilization rates from manure, (2) atmospheric ammonia levels in poultry houses, (3) poultry performance (weight gains, feed conversion, etc.), (4) energy use, and (5) P runoff from small watersheds. Two farms in NW Arkansas, USA, were utilized for this study. Alum was applied at a rate of 1816 kg house−1 in half of the houses at each farm after each flock of birds and incorporated into the manure. The other houses were controls. Ammonia volatilization rates were reduced by 97% with alum applications for the first four weeks of each growout. Birds grown on alum-treated manure were significantly heavier and had better feed conversion that birds grown in control houses. Energy use was also lower in alum-treated houses due to reduced ventilation requirements to remove ammonia (NH3). An economic analysis indicated that this best management practice was very cost-effective, with a benefit/ cost ratio of 1.96. Phosphorus runoff from normal and alum-treated poultry manure was evaluated from field-sized plots (1 acre each) for 3 years. Phosphorus concentrations in runoff water from alum-treated manure were 75% lower than normal manure. These results indicate that treating poultry manure with alum is a cost-effective best management practice that reduces nonpoint source P runoff.