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Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  Pp. 473-476 in Total Maximum Daily Load (TMDL) Environmental Regulations–II Proceedings of the 8-12 November 2003 Conference (Albuquerque, New Mexico USA), Publication Date 8 November 2003.  .(doi:10.13031/2013.15600)
Authors:   K. A. Rolf, J. S. Strock, D. J. Mulla, and P. H. Gowda
Keywords:   TMDLs, Nonpoint source pollution, Organic agriculture, Cropping systems

Loss of nutrients and sediment through agricultural runoff contributes to surface water pollution. This study was conducted to determine whether differences exist in subsurface runoff water quantity and quality between two cropping systems. The study examined the effect of conventional versus organic farming practices on nitrogen, phosphorus, and sediment loss from glacial till soils in southwest Minnesota. The conventional systems consisted mainly of row crops corn (Zea mays L.) and soybean (Glycine max L.), while the organic system contained corn, soybean, oat (Avena sativa L.), alfalfa (Medicago sativa L.), and other perennial species. Subsurface drainage flow and nitrate-nitrogen, ammonium-nitrogen, phosphorus, and sediment concentrations were collected from both cropping systems. The Agricultural Drainage and Pesticide Transport (ADAPT) model that incorporates weather, crop, soil, and drainage system input parameters was used to predict nutrient transport from these field-scale cropping systems. Model simulations from the different management systems were used to predict nutrient loadings from subsurface drainage to surface waters. Information from this project has potential implications on the Total Maximum Daily Load (TMDL) process in the development of alternative management strategies for mitigating the effects of agricultural nonpoint source pollution. Data on cropping system history and water quality data from 2002 will be presented.

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