"The most important thing demonstrated by our study is that grazing can be a positive tool for range management," said Keith Weber, director of the ISU GIS Training and Research Center. "Our study plot that featured intense, short-term grazing had 10 percent more soil moisture than other sites."
Weber and ISU GIS Ph.D. alum Bhushan Gokhale published the study "Effect of grazing on soil-water content in semiarid rangelands of southeast Idaho" in the Journal of Arid Environments.
The study, funded in part by a $1.5 million NASA grant, was conducted on three plots of land on the ISU O'Neal Ecological Preserve near McCammon, Idaho. One plot featured rest/rotation grazing practices where 300 head of cattle where grazed for 30 days; a second plot was not grazed; and a third, smaller plot, featured 125 head of cattle grazing for six days.
"The density of grazing in the smallest plot was six times as much as what occurred on the rest/rotation plot," Weber said.
At the end of the study, all three plots all had roughly the same amount of shrub and grass cover as they had prior to the study. The difference between the three plots, however, was that the small plot grazed intensely for a short period of time had 10 percent greater soil moisture compared to the other two.
"There was significantly more litter, which is essentially trampled down dead grasses, in the smaller plot," Weber said. "That litter acts as a mulch for the soil and grasses. Without the high density of animals grazing in a small area, there is less litter, less mulch and dryer soils."
In the semiarid American West, including the Intermountain Region, conserving water is key, and a 10 percent increase in soil moisture is significant. Weber noted that while there are many variables in livestock grazing, his study has shown that prescribed grazing can increase soil moisture, leading to more grass and increased biomass.
"In the West, water is key," Weber said. "If we can capture and retain it by changing some grazing practices, it could really make a different in range production and benefit the economy of rural Idaho." FG
—Idaho State University news release
