Build drought-resistant soil via boom-bust grazing

Wibaux, Montana, rancher Ray Banister was 28 when he began leasing the family ranch from his stepfather in 1970. Though he'd been working on the outfit since he was 9 years old, he still had a lot to learn about pulling the operation through the droughts that repeatedly returned to the region.

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Grass for the cow herd was often in short supply and hay hard to find. Then he stumbled across the chance to lease grazing land that had been rested for a year.

The robust response of the range to the rest transformed Banister's ideas about grazing and set him on the course of evolving his signature boom-bust grazing system involving relatively short, severe grazing periods followed by yearlong rests. Over the years, the grazing system helped Banister build drought-resistant soil while earning a slew of conservation awards in the process.

Study Reveals Benefits

A soil assessment study conducted on Banister's ranch in 2017 by Montana Natural Resources Conservation Service (NRCS) local and area staff confirmed the extent to which his boom-bust grazing has built soil health and achieved production stability. The study compared soil health and water infiltration on a sloping site in one of Banister's pastures with the soil health and infiltration of a neighboring pasture where annual, season-long grazing had been practiced. The grazing site on Banister's land had been rested the previous year.

"We wanted to see how the management of soil affects the amount of rainfall we can capture," says Katrina Johnson, NRCS district conservationist at Wibaux.

The study revealed that management can indeed make or break water infiltration and storage below ground, where it provides long-standing moisture for plants. "We found the water-holding capacity of the soil in the boom-bust system was much greater than the soil in the continuously grazed pasture," Johnson says.

The district staff installed soil-moisture sensors at 1-, 2-, and 3-foot depths in each location. On the season-long side of the fence, the soil moisture dried out at the 1-foot level by June 13. On the boom-bust side, the sensor at the 1-foot level continued to have moisture and was completely resaturated with a rainfall on July 3. That particular rain event failed to recharge the 1-foot sensor on the season-long grazing site, suggesting the rainfall ran off rather than infiltrated the soil.

"After the July 3 rain event, on Ray's side of the fence, the soil was even saturated down to the 3-foot level," Johnson says.

Infiltration tests on Banister's pastureland show that the first inch of rain is absorbed in 14 seconds. "The second inch is absorbed in 28 seconds," he says. There's no runoff."

The building over time of a porous structure in the silty clay soil is responsible for the rapid water-infiltration rate. "The soil has well-formed soil aggregates, giving it that healthy texture resembling cottage cheese," Johnson says. "Our resistance test showed more compaction on the season-long grazing site."

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The porous soil structure in the boom-bust grazing regimen is linked to "the build-up of litter and thatch on the soil surface," Johnson says, as well as to the rest the plants receive, which allows them to strengthen their roots.

"With the plant health and diversity in the boom-bust system, there's a massive amount of roots that go deep into the soil profile," she says. "In the continuous-grazing system, the plants were more shallow-rooted and less robust; the plants were not as healthy. It's important to have healthy roots because the roots put sugar exudates into the soil, and those sugars are food for the soil biology."

That the soil life gets plenty of food from plant roots in the boom-bust grazing was borne out by the results of a Haney soil health analysis. The biological activity measured in the soil in the boom-bust system was more than twice the activity in the continuously grazed rangeland.

An added benefit to the soil life in the boom-bust system compared with the season-long system are the lower soil temperatures resulting from the shelter provided by surface litter and plant canopy. The summer soil temperature in the boom-bust system was 52.2°F., as compared with 65.8°F. in the soil of the season-long grazing. The surface temperature in the boom-bust land was 84.1°F. as compared with 98.4°F. in the season-long acres. Excessive heat at the surface can kill soil biology.

The forage production measured by the NRCS staff showed the benefits of the boom-bust system. It yielded a total annual production of 3,290 pounds per acre compared with 1,945 pounds in the season-long system. When standing plant material from the rested year was included in the total, the boom-bust system yielded 5,092 pounds per acre, while the season-long system yielded 2,092 pounds. This previous year's plant material is part of the herd's diet in a pasture's grazing year. (See "Boom-Bust Grazing.")

This annual volume of forage production gives Banister the ability to stock pastures at a rate higher than his county's conventional stocking rate. "The average carrying capacity in this area is 28 acres per cow-calf pair," he says. "I'm running one cow-calf pair for every 17 acres."

Drought resilience is a hallmark of the system. "Even though we were in an extraordinary drought all summer long in 2021, the production in the pastures was normal," Banister says. "The hay production was a little less, but I was able to harvest enough to make it through the winter."

Like the pastures, Banister rests hayfields every other year, except for a light dormant-season grazing period.

In sum, in Banister's system, soil moisture and rest conspire to create drought-resistant conditions.

"How Ray has managed over time allows the soil to capture moisture," Johnson says. "He is able to capture every raindrop he gets, and the moisture becomes plant available. Then he provides an opportunity for plants to fully recover from grazing. His system is living proof you really can protect yourself from drought."

Learn More

Ray Banister, 406/891-0944

Katrina Johnson, 406/796-2211, katrina.johnson@usda.gov