Movement of nitrogen through an agricultural riparian zone: 2 - Distributed modeling

The Nutrient Transport and Transformation model (NTT) is a generalized fate, speciation and transport model capable of simulating the movement of nutrients in the environment. The hydrologic model is an energy-driven, distributed parameter model that couples surface and ground waters. The vertical discretization consists of overland flow, perched saturated layer, root zone, percolation zone, and groundwater. The chemical model is based on the mass balances of nitrate, ammonium ion, organic nitrogen, humus material, organic phosphorus, phosphate, litter and biomass in the unsaturated zone and the groundwater. Geochemical processes affecting the nitrogen species mass balance that are included are nitrification, denitrification, plant uptake, mineralization, litter partition, humidification, decomposition, and biomass growth (uptake) and respiration. The NTT model was used to simulate the fate, transport and speciation of nitrogen through a corn riparian zone using data collected during the summer months of 1992. The NTT model was shown to be capable of simulating the hydrologic and biogeochemical processes occurring in riparian zones. The root mean square error between the simulated and observed nitrate concentration is 1 mg/l. The model can be used in the design of riparian buffers for nonpoint source pollution control.