Benchmarking irrigation water use in producer fields in the US central Great Plains

Efficient use of freshwater resources is necessary to balance food production and long-term sustainability of irrigated agricultural systems. Here we developed a framework to benchmark irrigation water use relative to crop yield for individual fields based on site-specific weather and soil. Subsequently, we used the framework to diagnose on-farm irrigation management, in relation to crop production, in maize and soybean producer fields in Nebraska (USA). We found actual irrigation to be similar to estimated irrigation water requirement in about half of the fields (i.e. small water surplus). Remarkably, these fields attained yields similar to fields where actual irrigation exceeded water requirements (i.e. large water surplus). Underlying causes for water surplus included producer risk aversion in soils with low water storage capacity, use of coarse methods for scheduling irrigation, and tillage. Scenario assessment indicated that total irrigation volume could potentially be reduced up to 25%-40%, without hurting crop yields, by reducing current irrigation surplus in years with above- or near-average seasonal precipitation. About a third of the producer fields already achieved high yields with little water surplus, supporting the contention that achieving high productivity with less irrigation by better matching irrigation amounts in relation with crop water requirements are compatible goals. The proposed framework can be applied to other crops and regions provided there are well-validated models, local soil and weather datasets, and reliable field-level irrigation, yield, and management records.