The Agricultural Drainage and Pesticide Transport (ADAPT) simulation model was used to evaluate the relative effects of nitrogen application rate, tile-drain spacing, and tile-drain depth on NO3-N losses through tile drains for conditions that are typical of the Upper Midwestern USA. The ADAPT model, a daily time-step continuous water table management model, was calibrated and validated for tile drainage and associated NO3-N losses using long-term monitoring data measured on three experimental plots of a Webster clay loam (fine-loamy, mixed, superactive, mesic Typic Endoaquoll) under continuous corn (Zea mays L.) with conventional tillage treatment. For the calibration period, the model predicted mean monthly tile drainage and NO3-N losses of 4.6 cm and 6.7 kg ha?1, respectively, against measured tile drainage and NO3-N losses of 4.6 cm and 6.9 kg ha?1, respectively. For the validation period, the predicted mean monthly tile drainage and NO3-N losses were 4.0 cm and 6.1 kg ha?1, respectively, against measured tile drainage and NO3-N losses of 3.7 cm and 6.5 kg ha?1, respectively. Long-term simulations were made for a wide range of climatic conditions between 1915 and 1996 to evaluate the effect of drain spacing, drain depth, and N application rates on tile drainage and NO3-N losses. Simulation results indicate that much greater reductions in NO3-N losses occur with reduced N application rates than with increases in drain spacing or decreases in drain depth.
Journal of Environmental Quality
Minnesota Water Research Digital Library
Do Not Have Copyright Permission