Global irrigation contribution to wheat and maize yield

Abstract

Irrigation is the largest sector of human water use and an important option for increasing crop production and reducing drought impacts. However, the potential for irrigation to contribute to global crop yields remains uncertain. Here, we quantify this contribution for wheat and maize at global scale by developing a Bayesian framework integrating empirical estimates and gridded global crop models on new maps of the relative difference between attainable rainfed and irrigated yield (ΔY). At global scale, ΔY is 34 ± 9% for wheat and 22 ± 13% for maize, with large spatial differences driven more by patterns of precipitation than that of evaporative demand. Comparing irrigation demands with renewable water supply, we find 30–47% of contemporary rainfed agriculture of wheat and maize cannot achieve yield gap closure utilizing current river discharge, unless more water diversion projects are set in place, putting into question the potential of irrigation to mitigate climate change impacts.

How Can We Realize Sustainable Development Goals in Rocky Desertified Regions by Enhancing Crop Yield with Reduction of Environmental Risks?

“…Therefore, considering the local topography, fragmentation of cropland, and other environmental characteristics, the combination of both "soft-path" (capturing water resources in small and check dams) and "hard-path" (with large, centralized, capital intensive irrigation projects and water storage infrastructure) may be necessary to enable sufficient irrigation water to meet the demand for crop growth in the future [93]. Moreover, it is notable that the implementation of these development patterns is often limited by "economic water scarcity" resulting from the cost of building irrigation infrastructure under local financial conditions [94].…”

Insights on Nitrogen and Phosphorus Co‐Limitation in Global Croplands From Theoretical and Modeling Fertilization Experiments

“…The statistical methodology has been recently updated to improve the separation between water‐limited and irrigated yield potential (Wang et al. 2021). Alternative estimates of potential yield such as the ones simulated by Global Gridded Crop Models are also prone to huge uncertainties (Müller et al., 2017; Ringeval et al., 2021).…”

“…Such approaches have difficulty distinguishing irrigated and rainfed crops and thus, the here used Y pot could be in fact water-limited in some places (van Ittersum et al, 2013). The statistical methodology has been recently updated to improve the separation between water-limited and irrigated yield potential (Wang et al 2021). Alternative estimates of potential yield such as the ones simulated by Global Gridded Crop Models are also prone to huge uncertainties (Müller et al, 2017;Ringeval et al, 2021).…”

Historical simulation of maize water footprints with a new global gridded crop model ACEA

“…These models (such as LPJmL, EPIC, and DSSAT) typically simulate crop growth and water use from the underlying biophysical processes in the atmosphereplant-soil continuum for each grid cell independently or with couplings between grid cells (Müller et al, 2017). Due to high computational demands, there is a limited body of literature that applies GGCMs, with topics varying from irrigation demand estimation (McNider et al, 2015), climate change impact assessment (Rosenzweig et al, 2014;Ruane et al, 2018), and yield gap analysis (Wang et al, 2021). To our knowledge, global crop WFs have never been studied with GGCMs.…”