Closing the yield gap while ensuring water sustainability

Abstract

Water is a major factor limiting crop production in many regions around the world. Irrigation can greatly enhance crop yields, but the local availability and timing of freshwater resources constrains the ability of humanity to increase food production. Innovations in irrigation infrastructure have allowed humanity to utilize previously inaccessible water resources, enhancing water withdrawals for agriculture while increasing pressure on environmental flows and other human uses. While substantial additional water will be required to support future food production, it is not clear whether and where freshwater availability is sufficient to sustainably close the yield gap in cultivated lands. The extent to which irrigation can be expanded within presently rainfed cropland without depleting environmental flows remains poorly understood. Here we perform a spatially explicit biophysical assessment of global consumptive water use for crop production under current and maximum attainable yield scenarios assuming current cropping practices. We then compare these present and anticipated water consumptions to local water availability to examine potential changes in water scarcity. We find that global water consumption for irrigation could sustainably increase by 48% (408 km 3 H 2 O yr −1 )expanding irrigation to 26% of currently rainfed cultivated lands (2.67×10 6 km 2 ) and producing 37% (3.38×10 15 kcal yr −1 ) more calories, enough to feed an additional 2.8 billion people. If current unsustainable blue water consumption (336 km 3 yr −1 ) and production (1.19×10 15 kcal yr −1 ) practices were eliminated, a sustainable irrigation expansion and intensification would still enable a 24% increase in calorie (2.19×10 15 kcal yr −1 ) production. Collectively, these results show that the sustainable expansion and intensification of irrigation in selected croplands could contribute substantially to achieving food security and environmental goals in tandem in the coming decades.

Assessment of yield gaps on global grazed‐only permanent pasture using climate binning

“…We estimate that 90% yield gap closure on LG all lands would increase global protein production by 8.8 × 10 6 metric tons. In contrast, in rainfed crop agriculture, just 34% yield gap closure using expansion of “sustainable irrigation” in 4.53 × 10 6 km 2 of cultivated lands was estimated to yield 82 × 10 6 metric tons of protein per year (Rosa et al, ). This translates to 180 kg protein ha −1 year −1 , which would meet over 9 years of protein requirements for a 65 kg adult.…”

Global virtual water trade and the hydrological cycle: patterns, drivers, and socio-environmental impacts

“…Indeed, the quantitative analysis of water footprint and VWT focuses on water consumption and therefore does not inform about the sustainability of water resource exploitation (Gawel and Bernsen 2013). Thus, water footprint and VWT analyses need to be integrated with a water balance approach to compare the consumption rates with locally available water resources Mekonnen and Hoekstra 2016;Soligno et al 2017;Rosa et al 2018a). Indeed, literature on the globalization of water resources may miss a description of the phenomenon of VWT in the context of its hydrological implications.…”

“…Environmental flows describe the quantity, quality, and patterns of water flows required to sustain freshwater ecosystems and the ecosystem services they provide (Acreman et al 2014). Thus, blue water use can be analyzed based on its environmental and sustainability impacts , Yano et al 2016, Zhuo et al 2016, Rosa et al 2018a.…”

“…Renewable, yet finite, they are central for ecosystem functions, human wellbeing, and societal development (Ammerman and Cavalli-Sforza 1984, Falkenmark and Rockström 2004, Allan and Castillo 2007, D'Odorico et al 2010b. As a consequence of increasing human pressure, in some regions, water use is exceeding sustainable levels (Rosa et al 2018a). Therefore, we are living in what has been described as an era of water scarcity in which water resources available to agriculture may limit the planet's ability to meet the growing crop demand by human societies (Falkenmark and Rockstrom 2004, D'Odorico et al 2018, Rodell et al 2018.…”

Geographical Evolution of Agricultural Production in China and Its Effects on Water Stress, Economy, and the Environment: The Virtual Water Perspective

“…Limited water resources and food security are two of the main challenges the world will face in the future (Di et al, ; Smol, ). Agricultural production is both a resource provider and a consumer, because it consumes a large amount of water and land resources, while providing production and living materials (Rosa et al, ). In addition, agricultural production has a large impact on the environment due to massive emissions of greenhouse gasses and agricultural nonpoint source pollution (Bennetzen et al, ; Dalin & Rodriguez‐Iturbe, ; Gilbert, ).…”