SASKATOON – Decades of research into grazing systems shows no benefit to rotational over continuous grazing, says an Amer ican researcher, yet ranchers say rotational systems work and continue to promote them.
That disconnect is a source of angst for scientists, said Dr. Justin Derner, who heads the rangeland resources research unit at the United States Department of Agriculture’s Agricultural Research Service in Cheyenne, Wyoming.
He said overwhelming scientific experimental evidence indicates rotational grazing provides no benefit in terms of animal production or results in changes to vegetation, but ranch managers have shown that it does work for a variety of reasons, including those two.
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Derner said the reason is simple.
“Scientists have taken the human element out of our equations,” he said at the recent beef and forage symposium. “We can’t control for that.”
Replicated scientific studies are so tightly controlled that all possible variables, including management differences, are eliminated.
Most studies are also done on smaller acreages and in shorter time periods than ranchers would use.
Derner said researchers have to find ways to introduce the effects of human involvement and still retain scientific integrity.
There are two ways to do that, he said in an interview.
Scientists could establish a focus group of strategic producers and allow them to make decisions on the research. The researchers would then study the effects of the decisions on their research lands.
The other way to do it is to take the research to ranches and see how it works. This would require a broad approach with a series of researchers.
“That’s the way we can actually showcase science in the real world versus doing science in more of a vacuum,” Derner said.
Researchers could follow a couple of producers over an extended period or take a cross-section of small, medium and large operations and track management differences and outcomes.
“That seems to be the approach a lot of folks are looking at,” he said.
Ranchers at the symposium indicated they use rotational grazing to achieve certain goals in their operations.
A long-term grazing experiment at Cheyenne, between 1982 and 2006, examined moderate versus heavy stocking rates and season-long versus short duration grazing.
Derner said stocking rate always made a difference in terms of animal gains. There was a slight decrease in gain in the short duration system.
However, there was no impact to vegetation in either system, although ranchers often say that certain types of plants have appeared or re-established.
In terms of wildlife, researchers found no effects on grassland birds, and a slight negative effect on deer from rotational grazing. Elk were affected by stocking rate but not the particular system.
“In general there’s a lot of false claims out there in the literature and few valid studies,” Derner said.
Stocking rate and weather account for much of the variation seen between systems, the study concluded.
Scientists now want to know why so many people continue to advocate grazing systems and why they work, and that’s where ranch-scale studies are needed.
Adaptive management skills are widely acknowledged but not well studied, Derner said.
He added that these findings were not really a surprise to the scientific community but more of a wake-up call.
“I think the mentality has been, ‘We’re great scientists. Give us the money. We do great things and trust us,’ ” he said. “ ‘Once we find out what it is we’ll tell you what it is and you will implement it.’ ”
Scientists and producers need to work together to leverage funds and resources to do better work, he said.
Derner said this is made more difficult by young researchers who are far removed from actual ranches and don’t feel comfortable talking to ranchers.
“A few of us with a little more grey hair are trying to bridge that gap and say we can make the connection.”
Scientists are also uncomfortable giving up the total control they have in experimental situations.
But Derner said research applied on the ranch level is critical.
“There’s a lot of great research that sits on the shelf. That doesn’t do any good for anyone.”
