Integrated crop water management might sustainably halve the global food gap

As planetary boundaries are rapidly being approached, humanity has little room for additional expansion and conventional intensification of agriculture, while a growingworld population further spreads the food gap. Ample evidence exists that improved on-farmwatermanagement can close water-related yield gaps to a considerable degree, but its global significance remains unclear. In this modeling studywe investigate systematically towhat extent integrated cropwatermanagementmight contribute to closing the global food gap, constrained by the assumption that pressure onwater resources and land does not increase. Using a process-based bio-/agrospheremodel, we simulate the yield-increasing potential of elevated irrigationwater productivity (including irrigation expansion with thus savedwater) and optimized use of in situ precipitationwater (alleviated soil evaporation, enhanced infiltration, water harvesting for supplemental irrigation)under current and projected future climate (from20 climatemodels, with andwithout beneficial CO2 effects). Results show that irrigation efficiency improvements can save substantial amounts of water inmany river basins (globally 48%of non-productive water consumption in an ‘ambitious’ scenario), and if rerouted to irrigate neighboring rainfed systems, can boost kcal production significantly (26%global increase). Low-tech solutions for small-scale farmers onwater-limited croplands show the potential to increase rainfed yields to a similar extent. In combination, the ambitious yet achievable integratedwater management strategies explored in this study could increase global production by 41%and close the water-related yield gap by 62%.Unabated climate changewill have adverse effects on crop yields in many regions, but improvements inwatermanagement as analyzed here can buffer such effects to a significant degree.