Could cows heal the West?

Then it hit him: When protected on reserves, herbivores quickly became sedentary, leading to the same problems observed with chronic grazing by livestock. Savory’s insight: Grazing of a certain kind is integral to a savanna’s health. Migrating wildebeests and elephants recycle nutrients, he reasoned. The large quantity of urine and feces these large herds left jumpstarted the microbial activity necessary for healthy soil. Trampling broke the surface cap on the soil, permitting more water to flow into – rather than off of – the earth. The key to whether animals enhanced or destroyed rangelands was how long the animals remained in a given area. If they stayed too long, they killed grass and compacted soil. But if they moved through quickly, the plants survived and, newly fertilized, rebounded spectacularly.

“I realized we could use domestic animals to mimic animals on the move,” he says. “Use the maximum density of animals for minimum time, followed by adequate recovery periods for both soil and plants.”

But with its emphasis on more animals, not fewer, many say Savory’s method sounds too good to be true. The American West is hardly an African savanna, skeptics add. While the Great Plains hosted hordes of bison, ecosystems further west did not evolve with large numbers of migrating herbivores. (Semiarid western ecosystems were greatly shaped by wildfires, another periodic disturbance that recycles nutrients, however.) The grazers here – elk, bighorn sheep, rabbits, grasshoppers – affect the landscape very differently than do domestic cows, says George Wuerthner, author of “Welfare Ranching” and a critic of Savory’s. Cows simply can’t functionally replace wild animals, he says.

Scientific study generates debate
Others question whether Savo­ry’s ap­­proach delivers on its promise. A 2008 review in the journal Rangeland Ecology & Management concluded that many studies have failed to show that it worked better than continuous grazing. The paper generated debate at a recent meeting of the Society for Range Management in Ft. Collins, Colo. Many adherents of methods like Savory’s conclude that the science was flawed.

“I know for a fact that we can graze livestock in the West on a sustainable basis,” says Rick Knight, a professor of wildlife conservation at Colorado State University, Ft. Collins.

Keith Weber, a scientist at Idaho State University, Pocatello, has data that may help resolve the debate. In an ongoing experiment, he’s found tha­t intensely but briefly grazed pastures have higher soil moisture than either rested pastures or those grazed for long periods and then rested. He hopes to submit the results of his experiment for publication in a year.

Critics and proponents of these grazing methods do agree on one point: planning and monitoring – how engaged a rancher is with his or her land – makes all the difference.

“Livestock grazing can be sustainable, but it’s not a sure thing,” says rancher Jim Thorpe. “You’ve got to pay attention.”

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