Dynamics of NH4 and NO3 in Cropped Soils Irrigated with Wastewater. A Field Study

摘要

The objectives of this field study were: (1) to obtain information on the dynamic behavior of wastewater NH4 and NO3 in soils, (2) to determine the relative abundance of NH4 and NO3 in soils receiving wastewater, and (3) to evaluate the seasonal effect on the fate of wastewater NH4 applied to soils in a slow infiltration system. The study was conducted using an on-going test plot which contained two soil types and was covered with forage grass. Samples were collected in June and October to study the seasonal effect on the dynamic of N. The concentrations of NH4 and NO3 in the soil reached a daily, quasi-steady state condition. The seasonal effect on the relative amounts of NH4 and NO3, however, was significant. The vertical distribution of NH4 and NO3 was similar but there was always more NH4 than NO3. The concentrations of both NH4 and NO3 in soil profile were high at the surface and decreased with depth, consistent with the higher CEC, the slow movement of NH4 in soils, and the higher organic matter content in the surface. Both NH4 and NO3 concentrations were higher in the finer texture Charlton silt loam soil than in the coarser texture Windsor sandy loam soil. (Author)