Cover Crop and Fertilizer Management Impacts on Water Quality.

Eutrophication of freshwater aquatic ecosystems is intimately linked to phosphorus (P) fertilizer loss from agriculture productions. These algae blooms are harmful to humans, livestock, and wildlife. The Kansas Agriculture Watershed study was developed to understand the effect cover crops and fertilizer management practices have on reducing sediment and phosphorus loss via surface runoff. 18 watersheds approximately 0.5 ha in size make up the experiment. A 0.46 m H-flume and automated water sampling equipment installed at each watershed outlet measures runoff volume and collects water samples throughout a rain event. The treatment structure is a 2x3 factorial arrangement in a randomized complete block design with three replications. There are two levels of cover crop (with or without) and three levels of P fertilizer management (no P, spring injected P, and fall broadcasted P). The study was conducted in a corn-soybean rotation under no-till management. Winter wheat applied in the fall of 2015 was planted as the winter cover crop. The wheat was terminated chemically in the spring of 2016 prior to soybean planting. Water Analysis for total suspended solids, total phosphorus, and dissolved phosphorus is conducted by the Kansas State University Testing Laboratory. There were 27 runoff events between October 1, 2015 and September 30, 2016. Cover crop did not significantly reduce runoff volume overall but decreased erosion by 71%. Neither, cover crop or fertilizer management practice made a difference in total P loss. In the dissolved P fraction fall broadcast had 48% greater loss than did spring injected management. Counter to hypothesis, dissolved P load was greater from the cover crop treatment than it was from the no cover crop treatment on every runoff event. This resulting in a 48% increase in dissolved P loss overall when a cover crop was used. More research is needed to better understand the long term effects cover crops and fertilizer management practices have on sediment and nutrient loss in a no-till corn-soybean systems in northeast Kansas.