Assessing Crop Water Productivity under Different Irrigation Scenarios in the Mid-Atlantic Region

The continuous growth of irrigated agricultural has resulted in decline of groundwater levels in many regions of Maryland and the Mid-Atlantic. The main objective of this study was to use crop water productivity as an index to evaluate different irrigation strategies including rainfed, groundwater, and recycled water use. The Soil and Water Assessment Tool (SWAT) was used to simulate the watershed hydrology and crop yield. It was used to estimate corn and soybean water productivity using different irrigation sources, including treated wastewater from adjacent wastewater treatment plants (WWTPs). The SWAT model was able to estimate crop water productivity at both subbasin and hydrologic response unit (HRU) levels. Results suggest that using treated wastewater as supplemental irrigation can provide opportunities for improving water productivity and save fresh groundwater sources. The total water productivity (irrigation and rainfall) values for corn and soybean were found to be 0.617 kg/m(3) and 0.173 kg/m(3), respectively, while the water productivity values for rainfall plus treated wastewater use were found to be 0.713 kg/m(3) and 0.37 kg/m(3) for corn and soybean, respectively. The outcomes of this study provide information regarding enhancing water management in similar physiographic regions, especially in areas where crop productivity is low due to limited freshwater availability.