Alternative cropping systems to improve the quality of shallow groundwater

Alternative N management practices are needed to increase N uptake by plants and reduce the use of N- fertilizers to decrease NO3-N leaching to groundwater. The overall objective of this study was to evaluate the effects of two alternative cropping systems (a narrow-strip cropping configuration that included corn, soybean, and oats followed by a N- fixing berseem clover crop and three year rotation of alfalfa with corn in the fourth year) on the leaching of NO3-N to shallow groundwater, Experiments were conducted on 40, 0.4 ha field scale plots with three replications for each treatments. Each plot was drained with a single tile line which was intercepted for water quality monitoring. Four years data(1993 to 1996) on water quality from this study indicate that strip cropping and alfalfa treatments resulted in the lowest NO3-N concentrations in the tile water compared with all other practices evaluated at this site. The overall four years average NO3-N concentrations in the tile water were 7.0 and 2.8 mg/L for strip cropping and alfalfa plots, respectively. These results clearly indicate that forage crop rotated with corn and strip cropping systems could be used successfully to improve the quality of groundwater in comparison with the traditional corn-soybean production systems.