Science and Technology for Canadians

Grass Grows Green on the Range

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Summary

Our vision of the prairie pasture landscape dotted with grazing cattle seems timeless, but it's really a rather modern take on grassland vistas. Bison and wildfires once shaped the range now home to roaming ruminants. And as John Dormaar and Walter Willms have discovered, this changing of the guard can have an impact on the landscape. For instance, overgrazing can make the soil change from black to dark brown and diminish its water-holding capacity, making it drier. Experiments suggest that this change occurs once the rough fescue, a deep-rooted perennial grass, succumbs to overgrazing. Shallow-rooted plants then move in, and the land becomes susceptible to wind and water erosion. The scientists are looking for sustainable grazing solutions to help ranchers effectively manage their land resources.

Transcript of Video

Jill Deacon
The cattle industry is one of the backbones of the Alberta economy, and at the heart of that industry is the land... land for grazing, food for cows and other animals. Cattle were only introduced to the prairie grasslands a few generations ago, but already the look and feel of the land is changing. So scientists are trying to find a way to make sure that there's enough grass to go around for a long time to come.

Jay Ingram
Hard to imagine now, but vast herds of bison once grazed freely on these western grasslands. Wildfires triggered regeneration and renewal. The ecosystem was in balance, until the settlers arrived.

Dr. John Joordan
But when the settlers came in, about a hundred years ago, bison were eliminated and fire was stopped. And so now, all of a sudden, the equation under which this whole landscape had developed, and this grassland had developed, had changed because of the elimination of a couple of important components.

Jay Ingram
At the Stavely substation, between Lethbridge and Calgary, scientists are studying the impact of grazing on the grasslands, in order to develop sustainable grazing practices. Experiments here have been going on since 1949.

The first effort was to try to understand the relationships among grazing, plants, soil and water. Researchers established four areas where cattle grazed at different rates: at one extreme, one animal for every two acres, at the other, one animal per half acre.

When these areas were first evaluated in the 1970's, scientists found that the best setup was one animal for every acre and a half. At these numbers, efficient grazing was permissible, while at the same time maintaining the growth of important plant species, like Rough Fescue.

Rough Fescue is a perennial grass with a deep root system; the root can penetrate as much as a meter into the ground. If Rough Fescue disappears, shallow rooted plants take over; and the land is suddenly then susceptible to wind and water erosion. That's what happened in the heavily grazed areas in this experiment.

Dr. John Joordan
We were actually changing the inner microclimatic conditions within that soil to a drier soil. The soil colour changed from a black horizon to a dark brown horizon, and a result, the water holding capacity changed, the water started to run off instead of going into the soil, because again, it was kind of a naked landscape.

Jay Ingram
In 1986, the team went back to look at the soil again, this time focusing on its nutrient base, organic mass, and the ability to retain water.

They found that the patterns they'd noted back in the seventies had triggered permanent changes.

The pressure of grazing had forced the soil and plants into a new ecological balance. In fact, a new type of soil had been formed.

Dr. John Joordan
What the study really has shown is that with a different grazing practice, there is a cutoff point, and so to combine the amount of meat that can be produced, because that is the name of the game, the amount of meat that is being produced on this landscape, has to be in balance with the amount of vegetation, and that has to be in balance with the soil.

Jay Ingram
The team at Stavely is busy. They are looking at the effects of alien species brought from afar by settlers.

They are studying how nutrient levels in the soil and grasses are changing.

They wonder: how long will it take to rehabilitate a damaged grassland?

But perhaps the most important study is looking at the effects of grazing on water, and vice versa.

Dr. Walter Willms
We know from some of the studies, the observations we made over the last few years the water quality or the access to water, has a major impact on how livestock is produced. We found for example, that some...in some instances, depending on the source of the water, that the difference in production might be 20 to 30 percent...which has phenomenal ramifications for the rancher.

Jay Ingram
When cattle drink less, they eat less grass and don't grow as well. But nobody knows exactly why some cattle don't like to drink. It could be the taste of the water, or the presence of pollutants.

Scientists are testing water samples for algae, which may be toxic. They're looking for micro-organisms, like parasites, that might affect the health of the animals.

The global demand for meat is on the rise, and so, improved productivity is critical. The kind of long term research done at Stavely is fundamental to helping ranchers manage their land resources, and that means, sustainability.

Dr. John Joordan
Don't forget, we have families here that are in their third generation, and so they know what it's like to upset the apple cart. If they make a mistake this year, their children, their grandchildren may not be able to take over. And so, they have learned to understand that good stewardship is very, very important to carry on.

Jill Deacon
Today's Earth Tones was produced with the help of Agriculture and Agri-Food Canada.