The Influence of Cation Exchange Capacity and Depth of Incorporation on Ammonia Volatilization from Ammonium Compounds Applied to Calcareous Soils

The objective of this study was to determine the influence of soil cation exchange capacity (CEC) and depth of incorporation on NH3‐N volatilization from NH4+‐N compounds applied to calcareous soil. This study was conducted in the laboratory on soils with a wide range of CEC. An increasing CEC resulted in decreasing NH3losses. Ammonium sulfate produced higher soil pH values and NH3losses than did NH4NO3. The pH of the soil decreased with increasing NH4NO3application rates. With NH4NO3, percent NH3‐N losses decreased with increasing application rate; however, with (NH4)2SO4, percent NH3‐N losses increased as the application rates increased. Incorporation of the NH4+‐compounds into the soil reduced NH3losses. Increasing depths of NH4+‐incorporation resulted in reduced NH3loss. Losses decreased as the CEC of soil increased. The effectiveness of soil depth in reducing NH3loss was associated with soil water content. Decreasing the soil water increased the effectiveness of soil incorporation for reducing NH3losses. Two regression equations were developed to describe NH3losses with respect to CEC, soil pH, time, NH4+‐N application rate and temperature. Correlation coefficients were 0.86 and 0.81 for (NH4)2SO4and NH4NO3systems, respectively.