"Over the past five years, the hypoxic zone in the Gulf of Mexico has had an averaged size of 5,805 square miles. This is three times larger than the 1,900 square mile target set by the Gulf Hypoxia Task Force. It is estimated that nitrate (NO3-N) from artificially drained agricultural fields in the Upper Mississippi River Basin account for approximately 65% of nitrogen (N) entering the Gulf of Mexico, contributing to the hypoxic zone. Locally, the eutrophication of Illinois surface waters has considerable impact on drinking water quality, aquatic life, and the production of algae blooms impacting recreational ponds and lakes. The Illinois Nutrient Loss Reduction Strategy has set a goal of reducing the states nitrate-nitrogen load by 15% by 2025. There for the objective of this study where to investigate the impact of N fertilizer application timing and cover crops on the load of NO3-N in subsurface drainage leachate. This experiment was conducted at the Illinois State University Nitrogen Management and Tile Drainage Research Site in Lexington, IL. Treatments included a zero control (no N fertilizer and no cover crop), fall dominated N application (70% fall, 30% spring) with and without cover crops, and a spring dominated N application (20% fall, 80% spring) with and without cover crops. A total rate of 225 kg N ha-1 was applied to all treatments, except the zero control. Automated water samplers (ISCO 6712) were programmed to collect water samples that were analyzed for NO3-N, ammonium, and phosphorus concentrations. Spring cover crop sampling revealed an average biomass production of 1,361 kg ha-1 and an average total N uptake of 66 kg N ha-1. Results following the first season of cover crop integration indicated at least a 42% reduction in tile NO3- N leachate with the inclusion of cover crops within an N management system. With approximately 35% of Illinois crop land in tile drainage this data shows that cover crops could reduce nitrate loss significantly, working towards 2025's 15% reduction goal. "
Jefferson, Devin, "THE IMPACT OF COVER CROPS AND NITROGEN APPLICATION TIMING ON SUBSURFACE WATER QUALITY" (2019). University Research Symposium. 272.