NITROGEN FERTILIZER MANAGEMENT TO REDUCE WATER POLLUTION POTENTIAL

Both environmental and economic concerns have resulted in renewed interest in the potential for nitrogen loss under various climatic conditions. Experiments were conducted at three locations in Illinois to evaluate the effect of soil type, nitrogen rate, and excessive soil moisture levels on the potential for nitrogen loss. Addition of 10 cm of excessive water during the early part of the growing season resulted in N loss estimates of about 20 kg/ha on a silty clay loam at DeKalb and a sand at Havana. Increasing the excess water levels to 15 cm increased the N loss to 50 to 70 kg/ha at the same two locations, respectively. Since excessive rains in the fall prevented the collection of soil samples to use in monitoring nitrogen movement, conclusive results are not available to indicate the relative magnitude of loss from leaching and denitrification at these two locations. However, it is likely that a majority of the loss at the Havana site would have been through leaching, whereas at the DeKalb site most of the loss was probably due to denitrification