Journal or Book Title
Final Report: Gulf Hypoxia and Local Water Quality Concerns Workshop
Gulf Hypoxia and Local Water Quality Concerns Workshop
September 26-28, 2005
Wet, poorly drained soils throughout North America and Europe are often artificially drained with subsurface tile systems to remove excess (gravitational) water from the upper 1 to 1.2 m soil profile. Improved crop production that often results from drainage is in large part due to better physical conditions for field operations and a deeper unrestricted root zone for greater crop rooting, nutrient uptake, and yields. Removal of excess water by drainage lessens the potential for anaerobic conditions and consequently reduces the potential for nitrate to be lost from the soil profile by the process of denitrification. The combination of greater soil organic matter N mineralization with increased aerobic soil conditions, less N lost via denitrification, and increased transport of subsurface water results in higher nitrate concentrations in the receiving surface water bodies. Watersheds containing similar production systems and soils without subsurface drainage generate lower nitrate concentrations because anaerobic conditions exist more frequently. Under anaerobic conditions, denitrification predominates, resulting in nitrate losses as N gas to the atmosphere as well as economic losses to the farmer because of reduced available N.
American Society of Agricultural and Biological Engineers
Randall, Gyles W. and Sawyer, John E., "Nitrogen Application Timing, Forms, and Additives" (2008). Agronomy Conference Proceedings and Presentations. 33.