High Water Regime Can Reduce Ammonia Volatilization from Soils under Potato Production

This research was conducted with Biscayne marl soil and Krome gravelly loam from Florida and Quincy fine sand and Warden silt loam from Washington to determine ammonia (NH3) volatilization at various temperature and soil water regimes. Potassium nitrate (KNO3), ammonium nitrate (NH4NO3), ammonium sulfate [(NH4)2SO4], or urea were applied to the soil at a rate of 75 kg N ha . Soil water regime was maintained at either 20% or 80% of field capacity (FC) and incubated at 11, 20, or 298C, which represented the minimum, average, and maximum temperatures, respectively, during the potato growing season inWashington. Results indicated that the ammonia volatilization rate at 20% FC soil water regime was twoto three-fold greater than that at 80% FC. The cumulative volatilization loss over 28 days was up to 25.7%. Results of this study demonstrated that ammonia volatilization was accelerated at low soil water regimes.