Recently, I wrote about some of the climate adaptation research that the government and local agricultural industry has underway.
In the past, we handled drought by overgrazing or by destocking.
One now retired rancher told me a few years ago that his stocking of pastures and open range (Crown land) took into account drought years, by having the number of cattle that could be supported on the private and public pasture the driest of years.
Another school of thought is that an operation can “destock” by taking some cattle to the sales yard, or renting alternative pasture. It is best to have a plan for this if you can see it coming.
The rule of thumb is that grass production, at a point later in the season, can be predicted by the amount of rainfall 30 days before that point.
So if it is dry on the first of May, then production will be low on the first of June. So you have 30 days to plan for that eventuality. Sell or move the cattle.
Overgrazing is when you graze so hard or so often that all the root reserves of sugar get used up trying to respond to the grazing pressure. The plants just can’t get the leaves up to photosynthesize and thus regrow the plants.
In that case, resting the pasture for a much longer period will be necessary. Here some ranges need resting for over a year, just with normal good management, never mind any overgrazing.
In the March edition of the Canadian Cattlemen magazine, Jeff Melchoir reported on a three-year study across the prairies on grazing under drought and a probable hotter climate.
The findings: “Stocking rates are the key climate change adjustment.”
He also said, “Low defoliation rates and leaving lots of litter are best for coping with weather variations from year to year.”
In other words, if you leave over half the grass (more is better) then soil has cover, which prevents excessive evaporation of soil moisture and keeps the soil cooler. This blanket of insulation (old grass) will also keep the soil temperature up in fall, winter and spring and therefore enhances the soil biological activity.
The soil microbiology creates a little heat just like a compost pile does, as organic matter is broken down and becomes available as plant food.
The primary researcher from the University of Alberta is Edward Bork.
Another of their findings was that grasslands in an arid environment didn’t reduce its production as much as higher rainfall areas: “Mixed-grass vegetation has up to 85 per cent of its biomass below the ground as roots, which may render it less susceptible to drought.”
So locally, here in the Cariboo, this could mean that the farther east you go towards the mountains the impact on production might be greater because the plants are the type not used to being moisture stressed. This would be my observation, too.
So what to do? Don’t overgraze, that is, leave lots of grass behind. Don’t graze too early, tempting though that might be in this warm spring. Plants grow by a combination of heat and light, so grazing too early may use up sugars in the roots which creates the “jumping up” of early growth.
We need to do more trials and measure, but government is getting out of this work. You know the saying, “you can’t manage what you don’t measure.”
If we take care of the land it will take care of us.
David Zirnhelt is a member of the Cariboo Cattlemen’s Association and chair of the advisory committee for the Applied Sustainable Ranching program which started at Thompson Rivers University in Williams Lake this January.
