A Nonpoint Source Model for Land Areas Receiving Animal Wastes: II. Ammonia Volatilization

Abstract

ABSTRACT A simple conceptual model was developed, based on a state-of-the-art approach, to describe NH3 volatilization losses from land areas receiving animal manures. Environmental and soil factors influencing NH3 volatilization were also included in the model. Rate constants for first order relationship were estimated from the existing literature data. The sub-model described assumes that NH3 volatilization follows first-order kinetics. The rate of NH3 loss was shown by the model to occur in one or two stages. In the first stage, losses were relatively rapid with approximately 80 percent of applied NH3 being volatilized during the first week after applica-tion. Manures incorporated into soils with low CEC resulted in greater losses of NH3 compared to the manures incorporated into soils with high CEC. Losses of NH3 increased with increase in temperature and air flow rate above the soil surface. Correction factors for temperature, CEC, and wind velocity were presented to adapt the sub-model under varying soil and environmen-tal conditions.