SIMULATION OF NITROGEN DYNAMICS IN FLOODED SOILS1

Publisher Website
Google Scholar
Abstract
We developed a simulation model, NFLOOD, for describing simultaneous partitioning, transformations, and transport of nitrogen in flooded soils. Selected cases were simulated using NFLOOD to identify the relative gaseous losses of soil and fertilizer N via denitrification and NH3 volatilization. Model simulations identified the factors controlling gaséous N losses to be: (1) the rate of NH+4 and NO-3 diffusion from or into the soil, (2) nitrification (NH+4 → NO-3) rate in the floodwater and the soil, (3) the magnitude of diel variations in floodwater pH, and (4) the method of fertilizer N application. The results of the model simulations suggest that: (1) addition of fertilizer N to floodwater rather than to soil results in greater gaseous losses of N, (2) NH3 volatilization losses are important only with significant diel variations in floodwater pH and when nitrification rate is small, and (3) denitrification losses are directly related to rate of nitrification in the floodwater and the oxidized soil layer.