AMMONIA VOLATILIZATION FROM FLOODED SOIL SYSTEMS - A COMPUTER-MODEL .2. THEORY AND MODEL RESULTS

Our theory to describe the process of NH3 volatilization from flooded systems is that the rate of NH3 loss is principally a function of two parameters, floodwater NH3(aq) concentration and the volatilization rate constant for NH3, kvN. These parameters are governed by five primary factors, floodwater NH4-N concentration, pH, temperature, depth of floodwater, and wind speed. The NH3-volatilization model is executed with five primary factors as input variables. With the input of time, it predicts the NH3 loss for a specified period. The interactive effects of these factors were studied by individually varying one factor while maintaining the four other factors at their mean values; the same factor was also studied by maintaining a second factor at its highest and lowest values while the other three factors were kept constant at their mean values. It is seen that, by changing the existing conditions, the NH3-volatilization losses are increased or decreased appreciably. The sensitivity analysis shows that pH is the most sensitive and temperature and water depth are the least sensitive determinants affecting NH3 volatilization.