By improving the amount of food produced per volume of water consumed on farmland around the world, global food and water security could increase significantly, according to new research from the University of Minnesota.
Growing food uses more water than any other human activity, so it is in everyone's best interest that we grow food as efficiently as possible, said research leader Kate Brauman.
"Knowing how much water is used in agriculture is important, but understanding efficiency might be even more important," said Brauman. "When we are using water, are we using it effectively?"
In what's being called the first study to look at global water productivity for such a large range of crops, Brauman's team analyzed global crop production, water use and crop water productivity by climactic zone. Sixteen staple food crops were analyzed: wheat, maize, rice, barley, rye, millet, sorghum, soybean, sunflower, potato, cassava, sugarcane, sugar beet, oil palm, rapeseed (canola) and peanuts.
Combined, these 16 crops account for 56 percent of global agricultural output and take up 65 percent of the freshwater used for farming. Wheat, corn and rice are the major water users globally and irrigation water in dry regions goes mostly to wheat, rice and sugar cane, Brauman said.
The researchers found that the least water productive systems are disproportionately large freshwater consumers. In dry places, the researchers found that about 40 percent of water is used to produce only 20 percent of food calories. But the team found that there is great potential to close the gap.
By increasing the amount of food produced per liter of water evaporated or transpired - a ratio Brauman calls "crop per drop" - the least efficient farming areas could dramatically increase their food supply, the researchers calculated that in drier regions, bringing the very lowest performers up to just the 20th percentile could increase annual production on rain-fed cropland enough to provide food for an estimated 110 million people without increasing water use or using additional cropland. On irrigated cropland, increasing the crop per drop ratio could reduce total water consumption by as much as 15 percent in precipitation-limited regions of the world.
Specific solution on how to increase the crop per drop ratio will vary by region and climate, but the study was able to identify potential locations for interventions, crops to pay attention to, and opportunities for the biggest improvements in crop water management.
The research is published in the journal Environmental Research Letters.