A Montana heifer grazing Canada thistle
Every operation is different and each of you approach management in ways that suit you best. So providing comparisons for your particular operation is impossible.
For the purposes of a broad comparison though, let’s just look at Canada thistle nation-wide. A paper published in 2005 estimated 12 million acres of Canada thistle in the U.S. expanding at a rate of 10-12% per year. (Development of polymorphic markers for Cirsium arvense, Canada thistle, and their amplification in closely related taxa, T.A. Bodoslotta, Foley and Horvath, USDA-ARS-BRI, in Moecular Ecology Notes (2005)5 917-919) Based on that, if we use the 10% increase rate, it means that this summer there might be about 24 million acres of Canada thistle facing us.
Now here’s the reason we can’t reduce its rate of spread with herbicide: it’s too expensive. Just the herbicide alone for that many acres runs from $333 million to $580 million. Add to that the cost of fuel for running spray equipment, the labor involved, and we’re looking at a really big bill!
On the other hand, Canada thistle is equal to alfalfa in nutritional value, and educated cows will graze it level with grasses in the pasture. I haven’t been able to find out how many pounds per acre Canada thistle produces, so let’s use a low number. Let’s say it produces 800 pounds per acre. Using that low production it is still producing almost 19 million AUMs.
I know this is really rough math, but it does correlate interestingly with a
study done by the ARS in Miles City, Montana. Matthew Rinella developed a
weed calculator that he used to estimate that if leafy spurge were removed from a 17-state region, ranchers in the area could graze up to 200,000 more cows per year and save tens of millions of dollars. I’m just jumping directly from getting rid of the weed to eating it to arrive at the same increase in numbers of animals raised.
I’d love to hear your thoughts on this!
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