Kinetics of ammonia volatilization of anhydrous ammonia applied to a vertisol as influenced by Farm Yard manure, sorbed cations and cation exchange capacity

In laboratory experiments, effects of added Farm Yard Manure (FYM), sorbed cations and cation exchange capacity (CEC) on NH3 volatilization of anhydrous ammonia applied to a Vertisol were studied at 0.3 bar soil Moisture Tension and 25 ± 1°C. On addition of FYM or with increase in CEC the volatilization of retained ammonia was reduced while the effect of the sorbed cations was in the order : K‐Soil > Na‐Soil > Ca‐Soil > Mg‐Soil. The results suggest that the volatilization of retained NH3 followed First order reaction kinetics, with a rapid rate of volatilization in the initial 8 to 10 h followed by a retarded rate up to 144 h.