U research measures ‘crop per drop’

Researchers modeled improvements in crop production and water use.
June 12, 2013

Humans use more water for agriculture than anything else. Better management and distribution of water could help feed millions of people and tend to their day-to-day water needs.

University of Minnesota research published last month investigated the connection between water sustainability and food security.

Kate Brauman, a postdoctoral fellow with the University’s Institute on the Environment and lead author of the study, said the focus was on how much food could be produced from each drop of water.

“If we’re using water in agriculture,” she said, “are we getting enough food bang for our water buck? If we’re making tradeoffs, are we making good tradeoffs?”

The research took a theoretical approach to isolate the crops that use a lot of water for little caloric gain — like rice growing in a dry climate, for example.

Brauman said improving the irrigation and yield of these lowest-performing crops could use less water and produce more crops.

For rain-fed croplands, the research showed 110 million more people could be fed without using additional water every year by adjusting the low performers.

Improving the bottom- level crops for irrigated croplands could meet the annual household water demands of about 1.4 billion people.

“Obviously, you couldn’t necessarily get all of these gains,” Brauman said. But small “crop per drop” changes could still make a big difference, she said.

Making models a reality

The next step in making these gains a reality lies in work that researchers are doing on the ground.

Brauman’s study looked at 16 different crops, including wheat, legumes and some of the other biggest staple foods around the world.

IonE program director Paul West said finding out how to actually increase the yields is their next goal.

“We help … identify which crops in which places are having the biggest effect on water, on climate, on habitats,” he said.

Stefan Siebert, a study co-author from the University of Bonn in Germany, calculated how much water different crops need. Brauman then combined this data with information on crop yields from the University’s Global Landscapes Initiative to create the “crop per drop” models.

Developments in technology and soil and crop management have huge potential to increase crop yields and reduce gaps in many places, Siebert said in an email interview.

Here in Minnesota, better irrigation scheduling, management and technology has helped reduce water use, said Warren Formo, a Minnesota farmer and executive director of the Minnesota Agricultural Water Resource Center.

Many farmers in Minnesota have switched from an irrigation system that sprays water high into the air to a new system that lowers the water stream, reducing evaporation.

Formo said the “checkbook method” has been another major change to irrigation processes for efficiently using water. The method takes into account snowmelt, rainfall and the organic matter in soil to better determine how much water is needed for certain crops.

The global numbers are interesting, Formo said, but not excessively relevant to the work farmers are doing on the ground.

“Agriculture globally is much different than on a farmer’s individual 40 acres,” Formo said. “If you look at global averages and then look at my farm in Minnesota, it’s so different.”

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