Modeling nitrate leaching with a biogeochemical model modified based on observations in a row-crop field in Iowa

摘要: Prediction of nitrate leaching from cropland is crucial for preventing surface or ground water degradation. Accurate modeling requires simulations both soil hydrological and biogeochemical processes. This paper reports an attempt to improve existing model, Denitrification–Decomposition DNDC, estimation crop fields with tile drainage system. DNDC was equipped detailed processes nitrogen turnover but a simple module one-dimensional movement water. Observations nine tiles three different fertilizer treatments in 4 years (1996–1999) at experimental field Iowa were used model modifications. Preliminary comparisons observed discharge flow indicated that the original lacked recession character. To correct this deviation, new retention features added by: (1) adopting curve regulate gravity explicitly simulated profile (0–50 cm) (2) introducing virtual pool space between bottom modeled (50 lines depth placement (145 control flow. With these modifications, prediction fluxes improved. An adsorbed N created simulate buffering effect on amount available leaching. The Langmuir equation adopted adsorption desorption ammonium ions absorbents. modification enhanced capacity simulating free dynamics, nitrification, Sensitivity tests modified showed impact differences precipitation, texture, organic carbon content, application rates consistent observations reported by other researchers. study limited modifications hydrology could serve be useful sustainable agricultural management.