Reusing Irrigation Water from Tailwater Recovery Systems: Implications on Field and Stream-Level Nutrient Status

Abstract

Abstract. In the past few years, a significant number of tailwater recovery (TWR) systems have been installed by farmers and landowners in the Mississippi Delta Region through the Mississippi River Basin Healthy Watersheds Initiative. These systems have gained popularity as a way to capture agricultural runoff and provide water for irrigation during the growing season. In addition, these systems can potentially reduce nutrient loading to streams by retaining runoff on the farm and minimizing fertilizer application through recycling captured nutrients in irrigation water. This study examines the implications of nutrient concentrations in irrigation water from TWR systems on field-level nutrient balance as well as direct removal of nutrients from streams. To determine nutrient fluxes, water samples were collected from four locations in the TWR systems and storage reservoirs on two farms located in the Porter Bayou watershed in Sunflower County, Mississippi. Samples were analyzed for total suspended solids, total phosphorus, orthophosphate, ammonia nitrogen, and nitrate nitrogen concentrations. In addition, soil samples were collected and analyzed for Mehlich III extractable phosphorus to determine whether phosphate applied through irrigation would be retained for crop utilization or lost through runoff events. Nitrogen and phosphorus concentrations will be used to determine the total nutrient loading removed from streams and fertilizer delivery to crops.