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Remember the R’s: Rotate

Rotate pastures, time of year, and livestock type to allow critical rest and recovery of plants and roots

By Lynn Betts for Tri-State Livestock News

If you want higher grassland production in years to come, more resilience in a drought, and diverse grasslands that infiltrate and store rainfall to build healthy soils, think rotation. “In a grazing system, rotation is the pathway to the rest and recovery both plants and their roots need to build both healthy grasslands and healthy soils,” says Tanse Herrmann, state grazinglands soil health specialist for the USDA Natural Resources Conservation Service in South Dakota.

“The problem with season long grazing is the likelihood of overgrazing the most desireable plants livestock like most,” Herrmann says. “Longstanding research shows 50% of root growth stops when 60% of the leaf volume of plants are grazed,” he adds. “All root growth stops when 80% of the plant is grazed. Without enough plant growth to pump sugar downward to the roots, the roots don’t feed the soil biology. If a plant gets knocked down again and again in one season, it will eventually die, and other, less palatable plants move in. What you want instead is to offer plants the chance to rest and recover, to refresh and reach maturity.”

Rotate more than pastures



While most people think about rotating livestock through pastures, rotating livestock types and season of use from one year to the next also delivers dividends, Herrmann says. “Goats in particular, but sheep, too, like to browse and they will eat more woody and weedy species than cows,” Herrmann says. “Shifting the season of use is crucial because plants are in different stages of growth.”

Read the Grass



“I just grew up rotating pastures and just learning how to read the grass,” says Britton Blair, who is moving into a management role with his father Rich and uncle, Ed Blair, in a cow-calf operation north of Sturgis on a ranch that’s been in the family since 1954.

“I was brought up with no other way of thinking but to rotate pastures, and manage our grass, and the land,” Britton says.

“We try to rotate every two to six days, depending on pasture size and herd sizes,” Britton says. “We watch how much is being grazed; we have a take half/leave half mentality, and that’s what guides us on when it’s time to move on.” In good years, Ed adds, they take less than half, allowing them to stockpile grass for dry years.

Britton says they have their basic grazing principles and know how they want their grass to look, but to get to that, they’re always changing their rotation, with significant differences among ranches. “We might move every three days on this ranch, but on another one stay in a pasture for a month. Every year is different, too.”

Watch what the cows graze

“When we were in 4-H, Dad really enjoyed going out and finding different range plants. We spent half the summer out looking for range plants; that’s probably when I learned you can’t manage your range if you don’t know what’s out there,” Ed says. “We’ve AI’d cows for the last thirty years, and when we were out riding every day checking heats, I’d see what the cows were grazing. When you first go out, they’re eating the Kentucky blue. As you move on into the season, that’s when they start in on the western, and then some of the little blues and that type of thing. We’ve always run kind of a short-duration grazing system; we’ll go in early, to hit the pastures three or four days and move on, so we get that early flush. We manage for diversity and ground cover—we’ve seen big changes in that in the last 20 years.”

Steps to Rotation

 

Transitioning from season long grazing to a rotation? Tanse Herrmann has a few suggestions:

Complete an inventory of resources, and get help in developing a grazing plan.

Reach out to those with experience—NRCS, certified range managers, other producers.

Look for cost-sharing for developing the infrastructure you’ll need—fences, water supplies, etc.

A combination of temporary and permanent fencing may be best.

A combination of temporary and permanent water supplies may work best.

Be realistic in setting goals for stocking rates, length of time for forage improvement, etc.

Aim to reduce duration of grazing, and increase duration of rest.

Observe, observe, observe, and be ready to make changes to your plan.

Gauging Take Half, Leave Half

 

The widely used “take half, leave half” grazing rule of thumb’s intent is to stop grazing before root growth is affected. “It’s based on grass weight, not height,” Herrmann says. “You look at the weight of the grass leaves from the ground surface to the top of the plant. Two things we will often see is that the ‘take half’ equals the top two-thirds of the plant leaf growth, which often correlates to leaving 4”-5” residual plant height above ground. Your decisions on utilization should be based on your management objectives for each pasture.”

The most important thing, Britton says, is to “get that rest and that rotation going. Those cows love to get to that fresh pasture and love that grass, and they get pretty used to rotating. If you’re wondering if you should move them, usually they’ll tell you because they’ll be waiting for you at the gate.”

The Blairs see significant changes in forage diversity, rainfall infiltration, and grassland resilience over the past 20 years from more intense rotational grazing. Ed’s daughter-in-law Mary Blair (married to Ed’s son Chad) recently took a look at one of their pastures with their children, EC and Kate. Courtesy photos
Leaving half the grass after grazing generally means leaving at least 4 inches of standing grass.

Editor’s note: This is the second in a 6-part series recommending ranchers break down grazing management principles to memorable “R” actions that lead to resilient grazinglands on South Dakota farms and ranches.

–USDA/NRCS, Conservation Districts of South Dakota, and the Grasslands and Soil Health Coalitions of South Dakota

 


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