Agriculture is responsible for some 80% of total consumptive water use in the United States. (Consumptive use is that amount of water effectively lost to the system via evaporation, plant transpiration, incorporation in products or crops, or consumption by humans and livestock.) Clearly, when we think about water conservation, increasing water use efficiency in the agricultural sector is critical. And, there are some success stories out there. A report by The Pacific Institute, California Farm Water Success Stories (Christian-Smith et. al 2010), profiles a handful of farmers, like almond farmer Tom Rodgers, who reduced water use in some of his fields by up to 20% with careful monitoring and irrigation scheduling. Precision agriculture – using geographic information systems (GIS), infrared satellite imagery, modeling software, nutrient sensors and the like to evaluate crop density, water deficit, stress and other indicators, and smart tractors to apply inputs in a more targeted fashion – has also made tremendous gains.
Yet, the picture is infinitely more complex than the amount of water applied to fields. The American diet is extremely meat heavy, and as a result requires tremendous volumes of water embedded in feed and energy inputs. For reference, producing a serving of beef requires more than six times the water than growing a pound of green beans. And while we clearly need to reduce our dependence on meat – particularly factory farmed meat – this does not necessarily imply we all need to be vegetarian. Some really interesting work on the foodprints of residents of New York state by Chris Peters at Cornell University concludes that while a low-fat vegetarian diet requires 0.44 acres of land per person to produce, and a high-fat diet with lots of meat needs 2.1 acres, the optimal diet is a moderate-fat, plant-based diet with a little meat and dairy (and requiring 0.6 acres). The reason? While a vegetarian diet requires less land per person, fruits, vegetables and grains must be grown on high-quality cropland; meat and dairy products from ruminate animals can use lower-quality lands. Peters says “It appears that while meat increases land-use requirements, diets including modest amounts of meat can feed more people than some higher fat vegetarian diets.” Interesting, to say the least.
And then, of course, we have our antiquated use-it-or-lose-it Western water appropriation system that provides little incentive for water conservation (by agriculture, municipality, homeowners or industrial users), and has been pitting farmers against city dwellers and straining rural economies. A recent story in the Denver Post cites that 400,000 acres in Colorado were dried up between 2000 and 2005 (USGS data), and another 500,000 to 700,000 acres of irrigated croplands are likely to be lost by 2050. When water rights in affluent areas are trading for $50,000 per inch – enough to irrigate an acre of land – who do you think is going to win, the farmer or the wealthy second-home owner looking to build an aesthetic pond? As some Idaho ranchers have been known to say “If I lose my water, I lose my land”. While agriculture clearly is responsible for a slew of associated environmental problems, we have an equally dark problem: if we pave over much of our open agricultural land, how are we going to feed ourselves? The answer needs to be multi-fold – we need to stave off sprawl in favor of agricultural lands, but we also need to be smarter about the way we farm: We need to produce and eat local, organic, whole foods in a water- and energy-efficient manner.
The University of Nebraska’s new Water for Food Institute is putting on what looks to be a fabulous conference on the topic: Water for Food: Paths to Solutions, May 1-4, 2011.