Siphon irrigation in Tunisia.<br/>Photo: © FAO

Siphon irrigation in Tunisia.
Photo: © FAO

Better water management could halve the global food gap

Improved agricultural water management could halve the global food gap by 2050 and buffer some of the harmful climate change effects on crop yields.

Crop water management is a largely underrated approach to reduce undernourishment and increase climate resilience of smallholders. This is one major conclusion of a recent study by the German Potsdam Institute for Climate Impact Reserach (PIK).
If all farmers adopted well-known water management methods, global food production could expand as much as 41 per cent, the scientists in Potsdam have shown. They systematically investigated the world-wide potential to produce more food with the same amount of water by optimising rain use and irrigation. Investing in crop water management could substantially reduce hunger while at the same time making up for population growth. However, putting the findings into practice would require specific local solutions, which remains a challenge, the scientists note.

To gauge the impact of crop-water management techniques, the model considers rain and other climate data from 1901 to 2009 and simulates different scenarios of improvements in irrigation, conservation of soil moisture and rainwater harvesting.

Under the most optimistic scenario, production could increase “by more than 55 per cent in many river basins between the Middle East, central Asia, China, Australia, southern Africa and North and South America”, the researchers say.

Mulching and drip systems to counter climate change impacts 
The scientists took into account a number of very different concrete water management options, from low-tech solutions for smallholders to the industrial scale. Water harvesting by collecting excess rain run-off, for instance in cisterns, for supplementary irrigation during dry spells is a common traditional approach in some regions such as the Sahel region in Africa, but is under-used in many other semi-arid regions such as Asia and North America. Mulching is another option – the soil gets covered either simply with crop residues left on the field, reducing evaporation, or with huge plastic sheets. Finally, a major contribution to the global potential is upgrading irrigation to drip systems.
It is especially under ongoing climate change that water management becomes increasingly important to reduce food risks. The reason is that global warming is likely to increase droughts and change rainfall patterns, making water availability even more critical than before. The study sets out from a moderate CO2 fertilisation effect – plants take up CO2 and could hence benefit from higher concentrations in the air, although the magnitude of such an effect is still under debate. Under this assumption, the study shows that in most climate policy scenarios, water management can counterbalance a large part of the regional warming impacts on farming. Yet if greenhouse-gas emissions from burning fossil fuels are not reduced at all, in a business-as-usual scenario, water management will clearly not suffice to outweigh the negative climate effects.
Article: Jaegermeyr, J., Gerten, D., Schaphoff, S., Heinke, J., Lucht, W., Rockström, J. (2016): Integrated crop water management might sustainably halve the global food gap. Environmental Research Letters 11, 025002 [doi: 10.1088/1748-9326/11/2/025002]


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