Best Nitrogen Management Practices Can Reduce the Potential Flux of Nitrogen Out of the Arkansas Delta

Some studies have reported that nitrogen losses in the Arkansas Delta can contribute to the flux of nitrogen into the Mississippi River Basin, which can in turn contribute to the nitrate load that the hypoxia problem in the Gulf of Mexico has been attributed to. The need to reduce nitrogen losses in this region can be addressed with the development and validation of robust, new assessment tools that can be used to quickly evaluate management practices and their effects on the environment in terms of potential nitrogen losses and other factors. The recently developed concept of trading nitrogen in air and water quality markets can be used in conjunction with field studies to assess the potential benefits of nitrogen management. In 2008 and 2009, field studies were conducted to collect data to test the new Nitrogen Loss and Environmental Assessment Package (NLEAP) and its ability to simulate nitrate dynamics for different cropping systems grown in three different locations in the Arkansas Delta. Simulation by the NLEAP conducted for cotton, soybean, and corn grown in the Arkansas Delta showed that the model was able to simulate the effects of management on residual soil nitrate (P < 0.01). The simulation showed that residual nitrate can range from about 10 to 240 kg NO3-N ha(-1) in the top 1.5 m of soil, in agreement with measured values. In addition, long-term NLEAP simulation analysis showed that rotations of soybeans into corn systems significantly reduced emissions of N2O across this region and reduced NO3-N leaching losses at the field level.