AMMONIA VOLATILIZATION FROM ARABLE LAND AFTER APPLICATION OF CATTLE SLURRY .2. DERIVATION OF A TRANSFER MODEL

Ammonia, volatilized from animal manures after land-spreading, is one of the major sources of acid deposition in the Netherlands. A model for transfer of ammonia from arable land to the atmosphere after surface application or incorporation of cattle slurry is presented. The model can be used to study the interactions of the chemical, physical and environmental factors influencing volatilization losses and their combined influence on NH3 volatilization under field conditions. The model employs the following flux equation: R = k (C5-C(a)) where k is a transfer function, C(s) is the NH3(g) surface concentration and C(a) is the atmospheric NH3(g) background concentration. The rate of volatilization R can be calculated at any moment after application, provided K, C(s) and C(a) are known at this moment. The model therefore basically consists of modules which yield these variables.