Use of mineral amendments to reduce ammonia losses from dairy-cattle and chicken-manure slurries

Abstract

Two laboratory experiments evaluated the use of mineral amendments to reduce NH 3 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), CaCl 2(CC), gypsum (GP), rock phosphate (RP), superphosphate (SP), and triple superphosphate (TSP) at a 2% rate and surface-applied to Pugwash sandy loam (Humo-Ferric Podzol). The loss of NH 3 was measured over a seven-day period. The NH 3 volatilization was evaluated by two methods: direct measurement of volatilized NH 3 through capture in acid traps, and chemical analysis of initial and final nitrogen contents of manure and/or soil. During storage, NH 3 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 NH 3 volatilization was apparently due to the decrease in pH of the manure caused by the amendments.