Sep 26, 2008

Will Agricultural Yields Fall Off the (Water) Table?

by Tim Ogden

A number of experts argue that the food crisis that dominated headlines this spring and summer has diverted attention from a far larger problem: groundwater depletion. Raising agricultural output is the natural solution to rising food prices and food shortages. Yet doing so without considering the impact on water supplies and water usage will make the problem worse. Once groundwater is depleted, agricultural outputs will crash, regardless of the use of fertilizers, improved soil conservation or improved seeds.

The frightening realities of water over-consumption are abundantly clear in a new report from the German Research Centre for Geosciences. According to their scientists, only 10 percent of Iran receives sufficient rainfall each year to supply the water needs of the population. In other parts of Iran, the shortfall is made up by pumping water out of underground aquifers. Using satellite imagery from the last decade, researchers have discovered that pumping practices are causing land to subside and sink into the holes once filled with water. In some areas of Iran, the subsidence rate is 20 inches a year. While Iran seems to be an extreme case, the underlying issues are not dissimilar to those of the Ogallala Aquifer that provides water to much of the central United States. For more complete details on the US’s fresh water crisis, check out Cadillac Desert by Marc Reisner. Though almost 20 years old, the book remains one of the best for fully explaining America’s troubling history and future struggles with water use.

Agriculture is at the center of the water issue because agriculture is responsible for roughly 70 percent of global freshwater use. The International Water Management Institute estimates that 70 percent of that use is wasted. So clearly there are obvious steps that can be taken—including better pricing of water, as we’ve noted before. If in the rush to deal with the food crisis we focus only on increasing yields, the long term consequences will be far worse than the current shortages and inflationary pressures.