Tillage and Split N-Fertilization Effects on Subsurface Drainage Water Quality and Crop Yields

Field experiments were conducted to study the effects of no-till and conventional tillage, and single and slit N-fertilizer applications, for continuous corn production on the leaching of nitrate-nitrogen (NO3-N) through subsurface drainage water and below the root zone. The comparison between conventional and no-till was made by applying a single application of 175 kg-N/ha at the time of planting, and the comparison between single and split N applications was made for the no-tillage system. Six experimental plots, each drained with a single subsurface drain, were intercepted by installing sumps for measuring drain flow rates and collecting drainage water samples for NO3-N analyses. Also, four sets of piezometers were installed for deep water sampling. In the first year of the experiments, tillage and N-fertilizer management schemes did not significantly affect NO3-N concentrations in drainage. However, in the third year, the average NO3-N concentrations in drainage from conventional tillage plots were significantly greater than those of no-till plots when a single application of 175 kg-N/ha was made. The results of this study indicate that split N-applications totaling 125 kg/ha reduced NO3-N concentrations in drainage compared with a single, higher rate of application of 175 kg/ha for the no-tillage treatment