A stochastic benefit-cost analysis is used to analyze the profitability of irrigating from an Onarm water storage (OFWS) system using a center pivot irrigation system (CPIS) compared to a rained production system for corn and soybean in the Southeast while also incorporating risk in the form of stochastic prices, yields and weather. Findings indicate that producer’s decision to invest in an OFWS is dependent on the existing rate of returns and risk aversion levels. When costs are paid upront, net present values for irrigating from an OFWS are lower than that of rainfall when discount rates are just above 2%. Higher net present values for irrigation relative to rainfall production are realized when the cost of investment is financed rather than making an upront payment at higher discount rates. Investing in an OFWS on small farm sizes is not a good option for risk averse producers but, under extreme risk aversion levels, decision makers may prefer to irrigate and insure their revenue at higher coverage levels than depend on rainfall. Cost assistance opportunities for crop producers to prevent downstream flow of nutrients from production fields through the use OFWS should be more than 40% to make irrigation more desirable than dryland production at 8% and 10% discount rates.

Evaluation of an On-Farm Water Storage (OFWS) system as a Best Management Practice (BMP) for nutrient and sediment loading control and irrigation in East Mississippi has shown that the system can effectively reduce sediment and nutrient loading as it was able to capture 46 tons of sediment and 558 kg of phosphorus over the monitoring period. The system was also able to decrease nitrogen loading as shown from the nitrogen concentration in the captured storm runoff events although an accurate estimate could not be made using AnnAGNPS because adequate model input data was not available. The system was able to provide about 63 million gallons of water for irrigation as a result of which increased corn and soybean yield was also obtained in irrigated fields when compared to non-irrigated fields. Water from the storage pond used for irrigation did not have adequate nutrient recycling to reduce commercial fertilizer application.

The onarm water storage (OFWS) systems at Metcalf and Pitts farm in Porter Bayou Watershed were monitored for changes in nutrient levels and water withdrawal for irrigation from March 2012 to April 2013. Nitrogen and phosphorus levels were generally higher during the early part of the growing season. The OFWS systems can reduce nitrate and phosphorus in runoff up to 81% and 85%, respectively. However, the systems did not consistently reduce sediment and nutrients especially after significant rainfall and runoff events. The systems provided a total of 130 and 233 acreeet of recycled water for irrigating crops at Metcalf and Pitts, respectively, during the 2012 growing season. These amounts reflect significant savings in terms of groundwater. This study highlights the advantages of OFWS systems as structural BMPs to reduce nutrient loading into the Gulf of Mexico and to minimize groundwater withdrawals from the Mississippi Alluvial Aquifer.