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 NH 3 ‐N volatilization from NH 4 + ‐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 NH 3 losses. Ammonium sulfate produced higher soil pH values and NH 3 losses than did NH 4 NO 3 . The pH of the soil decreased with increasing NH 4 NO 3 application rates. With NH 4 NO 3 , percent NH 3 ‐N losses decreased with increasing application rate; however, with (NH 4 ) 2 SO 4 , percent NH 3 ‐N losses increased as the application rates increased. Incorporation of the NH 4 + ‐compounds into the soil reduced NH 3 losses. Increasing depths of NH 4 + ‐incorporation resulted in reduced NH 3 loss. Losses decreased as the CEC of soil increased. The effectiveness of soil depth in reducing NH 3 loss was associated with soil water content. Decreasing the soil water increased the effectiveness of soil incorporation for reducing NH 3 losses. Two regression equations were developed to describe NH 3 losses with respect to CEC, soil pH, time, NH 4 + ‐N application rate and temperature. Correlation coefficients were 0.86 and 0.81 for (NH 4 ) 2 SO 4 and NH 4 NO 3 systems, respectively.