We use more water for agriculture than for any other human activity on the planet, so water sustainability and food security are closely linked. And as demand for water increases — for domestic, industrial, and other uses, as well as for in-stream flows for nature, fishing, and recreation –demand for food expands as well due to our growing populations and changing diets. This dilemma will only create more pressure to optimize the efficiency of water use in crop production.
But how do we know where we might get more food “bang” for our water “buck”? I recently led a study evaluating how crop water productivity — the amount of crop produced per drop of water used — varies across the globe. We discovered that it varies significantly, even between places that have about the same climate. This shows that there is a “water gap” in some areas, which means they could be getting a lot more crop per drop.
The amount of variation we found in crop per drop among places with similar climates suggests a two-pronged approach. First, there are changes farmers can make to increase water productivity, and, second, the impact of those changes could be substantial. The on-the-ground changes farmers make — things like using more fertilizer to increase yields — will differ from place to place.
What a global study like this shows is that those changes could add up to something big. We found that if the worst-performing croplands improved their crop per drop by just a little bit, the rainfed ones could feed 110 million people each year without consuming more water, and the irrigated ones could save enough water to meet the annual domestic water demands of nearly 1.4 billion people without decreasing food production.
Because this is a global study, we were able to identify which of the 16 different crops we analyzed have the biggest “water gap,” and where the biggest gaps are located. Governments and aid organizations around the world can use this information to help decide which crops to focus on, in which places, and how to best boost water sustainability and food security.
Read the study and watch the video here.
Kate A. Brauman is a postdoctoral research scholar at the University of Minnesota. She is evaluating global trends in agricultural water consumption and researching hydrologic ecosystem services.