The challenge of raising beef and dairy in a desert

Science Notes: Irrigation to feed crops for cattle in western U.S. drops river levels

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Humans are using freshwater resources faster than they can be naturally replenished.

In the western United States, for example, water extractions from the Colorado River have exceeded total river flow, causing rapid depletion of water storage reservoirs.

In addition, as these water sources dry up, species of fish, plants and animals are also adversely impacted.

That creates questions about where beef should be produced in the world.

A new study published in Nature Sustainability shows that irrigation of crops for cattle feed is the greatest consumer of river water in the western United States, implicating beef and dairy consumption as the leading driver of water shortages and fish imperilment in the region.

Kyle Davis, assistant professor of Geography and Spatial Sciences and Plant and Soil Sciences, performed the crop water-use estimates for the study.

He says the researchers wanted to understand what sectors within the U.S. economy and which crops contributed most to unsustainable water use, as well as what regions of the United States were most vulnerable to that water loss.

Overall, Davis says that he doesn’t want to give the impression that all beef is bad, noting that in many places, cattle are important for converting grasses that humans can’t eat directly into edible material.

“Cattle play an important role in food security and nutrition, but their environmental impacts can be large. Ensuring that beef and cattle feed are produced in places where water resources are relatively abundant can help to achieve balance between satisfying our diets and protecting the environment,” says Davis.

Irrigation of feed crops is the single largest consumptive user at both regional and national scales, accounting for 23 per cent of all water consumption nationally in the U.S., 32 per cent in the western U.S. and 55 per cent in the Colorado River basin.

Alfalfa, for example, is a water-intensive crop that is planted on a large scale to support the beef industry in the western U.S. In addition, a crop like corn, which on its own is water-use efficient, is produced on such a large scale to support the cattle industry that it ends up requiring a lot of unsustainable water use.

After identifying crops and sectors that were contributing to unsustainable water use, the researchers estimated the implications for aquatic species in the western U.S.

Sixty fish species in the western U.S. are at an elevated risk of global extinction due to flow depletion, and 53 of those are primarily due to irrigation of feed crops.

“We see huge opportunities for farmers and ranchers to be appropriately compensated for helping resolve our water problems and thereby enhancing their incomes and benefiting their communities,” says Davis.

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