The effect of drainage water recycling on corn and soybean yields and water conservation for a drained field in Eastern North Carolina

Abstract

<b><sc>Abstract.</sc></b> The main objective of this study was to quantify the effect of Drainage water recycling (DWR) on corn and soybean yields for a research site in eastern North Carolina during 4 growing seasons (2018-2021) of a wide range of weather conditions. Two treatments were implemented at the study site: DWR and control (CT) treatment. The CT treatment was a non-irrigated field that was primarily drained by a surface drainage system. The DWR treatment had a subsurface drainage system that was used to drain the field during the wet periods of the growing season and sub-irrigated it during dry periods. A reservoir was used to collect surface runoff and subsurface drainage and sub-irrigate the DWR treatment. Results showed that the DWR reservoir stored enough water to meet irrigation requirements in 3 of the 4 growing seasons and provided 5 to 73 mm of irrigation to the DWR treatment. Subirrigation of the DWR treatment raised the groundwater table by an average of 15 cm. The shallower water table at the DWR treatment increased the upward movement of soil water by the capillary rise replenishing water in the plant root zone to meet crop evapotranspiration demand. DWR increased corn and soybean yields in all four growing seasons, compared to the CT treatment. DWR increased corn yields by 0.39 and 0.90 Mg ha^-1 (3 and 79%) and soybean yields by 0.40 and 0.66 Mg ha^-1 (12 and 34%). Higher yield benefits were attained for the years with low precipitation by providing irrigation during the critical crop growth stages.