Ammonium and ammonia sorption on Broiler Litter and Cake

Abstract

Ammonia emission from broiler houses is a major concern because of its impacts on the environment. To reduce ammonia emissions, it is necessary to understand the fate of ammonia/um in the broiler litter. In broiler litter, uric acid and urea hydrolyze to ammonium (NH4+) and a fraction of NH4+ converts to ammonia depending on pH and temperature. Further, NH4+ undergoes solid-liquid partitioning and the ammonia fraction is partitioned among the solid, liquid and gas phases in the litter. Ammonium partitioning between solid and liquid phases in boiler cake (primary feces and spilled feed on the surface) and litter (dissolved fecal constituents and bedding beneath the cake) were measured at different pH values and dissolved ammonium concentrations. In broiler litter, Freundlich, linear and Temkin isotherm provided the best fit at pH of 4, 6, and 7, respectively. In broiler cake, linear isotherm provided the best fir at pH 4, 6, and 7. Ammonia partitioning among solid, liquid, gas phases was also measured using litter with different moisture contents. Under the test conditions, ammonia sorption increased with moisture content from 0% to 25% and maximum of ammonia sorption was 4,230 mg/kg at 25% moisture content and then decreased with increasing moisture content from 35% to 55%. Litter at 0% moisture content adsorbed > 2,800 mg/kg of ammonia, more than sorbed by litter with moisture content at or above 45%. The results of ammonium and ammonia sorption studies on litter will provide information to simulate litter nitrogen dynamics more accurately.