Farmscape for January 10, 2008  (Episode 2705)

Research underway in southwestern Manitoba is comparing various cattle grazing systems in an effort to develop management practices that will help farmers protect their land from drought.

Researchers with the University of Manitoba are comparing five cattle grazing systems, continuous grazing, time controlled rotational grazing, twice over rotational grazing, stock pile grazing and a plot where animals are not grazed on six sites including three native pastures in Cartright, Shilo and Rapid City and three tame forage sites at Souris Pipestone and Goodlands.

Dr. Martin Entz, a professor of agronomy with the department of plant science, says grazing impacts plant growth which, in turn, affects the plant's ability to access water.

Clip-Dr. Martin Entz-University of Manitoba

Grazing, the act of defoliating a plant, doesn't only affect the above part of the plant.

It also affects the roots.

If the plant is defoliated often what you get is a pasture plant, whether it's native or tame, that has very shallow roots because the roots are essentially pruned every time the plant is defoliated.

The way that grazing can affect the water balance is by allowing the roots to grow deeper and the deep roots to be maintained as productive roots.

There's a famous picture from Lethbridge where there's a heavily grazed plant and lightly grazed plant and they looked at the roots and they washed out the roots and it's pretty clear that defoliating the plant in a continuous grazing system reduces root growth which means the plant doesn't have access to water.

So by changing the grazing system to, for example, a twice over system or even a time controlled rotational grazing where you allow the plant to recover from its defoliation, that means the roots also have a chance to recover and to grow deep and have access to water.

In that way grazing affects the plant's ability to gather water.

Dr. Entz says the plots will be cored to see how the roots are affected under each system to determine how plant growth is impacted over a four year period and how these systems impact soil carbon.

For Farmscape.Ca, I'm Bruce Cochrane.

       *Farmscape is a presentation of Sask Pork and Manitoba Pork Council