USE OF MINERAL AMENDMENTS TO REDUCE AMMONIA LOSSES FROM DAIRY-CATTLE AND CHICKEN-MANURE SLURRIES

Two laboratory experiments evaluated the use of mineral amendments to reduce NH3 volatilization from dairy- and poultry-manure slurries during storage or when applied to soil. Fresh manure was amended at a 1% and a 3% rate with superphosphate (SP), rock phosphate (RP), and gypsum (GP) and stored for 30 days. Anaerobically stored manure was amended with Na-bentonite (BT), CaCl2 (CC), gypsum (GP), rock phosphate (RP), super-phosphate (SP), and triple superphosphate (TSP) at a 2% rate and surface-applied to Pugwash sandy loam (Humo-Ferric Podzol). The loss of NH3 was measured over a seven-day period. The NH3 volatilization was evaluated by two methods: direct measurement of volatilized NH3 through capture in acid traps, and chemical analysis of initial and final nitrogen contents of manure and/or soil. During storage, NH3 volatilization was reduced by SP and GP in dairy manure, but none of the amendments effectively reduced volatilization from poultry manure. Ammonia volatilization from surface-applied manure was reduced by TSP, SP, CC, and GP treatments to dairy manure and by CC and SP treatments to poultry manure. The reduction in NH3 volatilization was apparently due to the decrease in pH of the manure caused by the amendments.