NITRATE CONCENTRATIONS IN DIFFERENT SOIL COMPOSITIONS IN A SATURATED RIPARIAN BUFFER ZONE

Agricultural runoff is a major issue facing the Mississippi River Basin. It results in nutrient runoff making its way into sources of drinking water or culminating in places such as the Gulf of Mexico where it contributes to the dead zone. Riparian buffer zones (RBZ) may present a solution to this problem. RBZs are an area of natural vegetation, in this case prairie grass, that presents a barrier between the stream and the neighboring corn/soybean fields. Biochemical interactions within this barrier reduce many chemicals found in agricultural runoff, such as nitrate. This study focuses on an RBZ located in central Illinois, USA, near Hudson. A tile diversion box diverts tile water from the neighboring fields into the saturated RBZ, through which it drains into the Kickapoo Creek. There are several locations throughout the site where four nested wells reside; two being in topsoil and two in a sand-gravel layer. Nitrate can be measured from the varying well depths to show which soil composition is most effective in eradicating nitrate. Using data collected over the last few years, we explored how soil compositions influenced nitrate reduction. Nitrate may be affected by different soil compositions that surround the wells, specifically in the topsoil rather than the sand-gravel layer due to the topsoil hosting vegetation. Nitrate concentrations are lower in the direction of the stream, but it is unclear which soil composition is responsible in eliminating the nitrate most effectively. Discerning which soil composition is most effective can lead to the development of more efficient RBZs, and therefore contribute to the health of waterways nationwide.