THE EFFECT OF COVER CROPPING AND AGRICULTURAL MANAGEMENT ON SURFACE WATER QUALITY IN A SMALL-SCALE WATERSHED IN CENTRAL ILLINOIS

Agricultural management practices (e.g. high rate of fertilization) to improve crop yields have resulted in the degradation of environmental quality by increasing nutrient leaching in the surface water and groundwater. Particularly, drainage water from agricultural lands of the Midwest is heavily impacting the environment in the Mississippi River basin and the Gulf of Mexico. As a result, management practices that sustain crop yields and improve environmental qualities are needed. Thus, the focus of this study is to understand the effect of cover cropping and agricultural management practices (e.g. crop rotation) on nutrient load reduction in a small-scale experimental watershed (area~5.5 km2) in Central Illinois. In this watershed, cover crops have been planted for 3 consecutive years (2015-2017) by covering 48 percent of the watershed area, and all hydrological and environmental quality indicator variables (e.g., rainfall, discharge, nutrients, etc.) have been collected using automated storm water sampling at higher temporal resolution (15 minutes) near the outlet of the watershed.. The relationship between hydrological and nutrients water quality variable have been investigated. Further, to understand the effect of the cover cropping, a hydrologic model using the Soil Water Assessment Tool (SWAT) have been utilized. The crop rotation of Corn-Soybean shows a lower reduction of Nitrate as compared to continuous corn-corn planting which might be due to denitrification or mineralization of Soybean residue as compared to Corn residue. The implementation of the cover crop has a significant role in the reduction of nutrient loads in areas where NO3-N loads are high due to management practices such as the use of fertilizers and biomass residue of N rich crops on the farmland.