Developing DIRT: A Drought Irrigation Response Tool for Furrow Irrigators

Highlights Rapid depletion during drought of groundwater, the primary resource for irrigators in Louisiana, must be addressed to protect aquifer health. A previously developed and tested soil water balance was used to generate an irrigation scheduling web tool. The goal of facilitating the determination of the most appropriate day to initiate irrigation events was met with minimal bias. Further improvements to the web tool must balance its simplicity to prevent barriers to adoption. Abstract. Drought is the most expensive extreme weather risk to Louisiana agriculture, accounting for 95% of projected crop losses by 2050. Predicted shifts toward more frequent and intense drought will increase the need for supplemental irrigation when aquifer withdrawals already exceed recharge rates. Thus, the objective of this research was to describe and demonstrate the Drought Irrigation Response Tool (DIRT), a freely available, web-based, user-interactive decision support tool for agricultural irrigators that provides site-specific strategies appropriate for concurrent drought risk. DIRT’s soil water balance calculation provides a simple representation of volumetric water content (VWC) throughout the crop season for multiple crops, such as corn and soybean production systems. Four on-farm demonstrations were used to observe soil moisture and compare it. The goal of facilitating the determination of the most appropriate day to initiate irrigation events was met in all four datasets, with minimal bias from DIRT. Thus, despite some less-than-ideal accuracies for precise hydrological modeling applications, DIRT is useful in practice for agricultural applications. Further improvements to the model, such as adding considerations for infiltration, refining soil-type selections that affect soil physical properties, and improving various assumptions built into crop growth and weather inputs, must be balanced against the simplicity of the tool to prevent barriers to adoption. Future research should compare DIRT’s yield and use efficiency with other irrigation scheduling methods.