ARS | Publication request: SURFACE WATER QUALITY RESPONSE TO A NITROGEN FERTILIZER BMP AT THE WATERSHED SCALE

Submitted to: Soil and Water Conservation Society
Publication Type: Abstract
Publication Acceptance Date: July 17, 2002
Publication Date: September 15, 2002
Citation: DINNES, D.L., JAYNES, D.B., KARLEN, D.L., MEEK, D.W., CAMBARDELLA, C.A., COLVIN, T.S., HATFIELD, J.L. SURFACE WATER QUALITY RESPONSE TO A NITROGEN FERTILIZER BMP AT THE WATERSHED SCALE. SOIL AND WATER CONSERVATION SOCIETY. 2002. V. 57(5). P. 308.

Technical Abstract: Agricultural field drainage systems have a significant impact on water quality because they behave like shallow direct conduits to surface waters. Nitrogen (N) is often transported with agricultural drainage water and has been implicated as contributing to hypoxia in the Gulf of Mexico. In 1997, we implemented a N fertilizer best management practice (BMP) on corn production fields in a midwestern tile-drained agricultural watershed to determine its impact on water quality. The N fertilizer BMP is designed to better match N rates and timing of application to crop needs than conventional practices. This is the first project ever to examine a N fertilizer BMP at the watershed scale. At the time of project termination in December 2000, the treatment watershed had a significantly lower nitrate-N concentration (7.3 ppm, or 41.5%, reduction) than the control at the 95% confidence level. These results suggest that by implementing N BMPs on tile-drained agricultural landscapes, we should expect improved water quality. Also, applied N rates and timing of application are important factors to consider in regard to improved water quality. Attempting to manage one of these factors without the other will likely produce diminished environmental returns compared to those found from this research.