LAUSR

Nutrient loading from conventional row-crop production systems impairs surface waterbodies in the mid-southern USA. This study was conducted to determine whether minimum tillage and winter cover crops can decrease nutrient loading in surface runoff from conventionally tilled row-crop fields. The effects of winter cover crops and minimum tillage on N and P loading from a corn (Zea mays L.)-soybean [Glycine max (L.) Merr.] rotation system were investigated on production fields in northwest Mississippi using a split-field approach. As measured at the edge of the field, minimum tillage with cover crops had no effect on surface runoff from production fields with regard to N or P loading (p > 0.10 for all nutrient loads), discharge (p > 0.10), or loss of suspended solids (p > 0.10). Minimum tillage and cover crops decreased sediment and nutrient concentrations in runoff for total N (p = 0.05) and total P (p = 0.09) but had no effect on other nutrients of interest. While these practices decreased total N concentration by 36% in surface runoff to receiving waters, this reduction was only seen when above ground cover crop biomass was present (p = 0.07). Regardless of the time of year, minimum tillage with cover crops decreased total P concentration in surface runoff by 27% (p = 0.09). These data indicate that it is unlikely that minimum tillage and cover crops will affect N and P loading while transitioning to a conservation production system in the mid-southern United States. This article is protected by copyright. All rights reserved.