A Grazing Survey of the Spring Creek Preserve

If it’s grassy, graze it. That’s the philosophy in Southeast Wyoming, where ranches span hundreds of thousands of acres and permits allow livestock to roam on public lands, too. Range management is an essential tool of responsible stewards – ranchers aim to maximize the agricultural productivity of the land while also protecting its biodiversity so that forage can replenish. It’s a balancing game, and a science with many rules. I had a conversation about these rules with the owner of Rancher’s Supply in Rock River, and it started my asking questions about the grazing potential of the Spring Creek Preserve. The Preserve was part of a ranch before it was owned by Pitt, and is still leased for grazing in the late summer. I know it has some value, but by trying my hand at range management methods, my project aims to define that value as a carrying capacity of livestock.

Grazing is quantified by Animal Units: the forage, in pounds, that a 1,000 pound animal will consume in one day at a normal growth rate. This is equal to about 2.5% of their body weight, so 25 pounds of forage per day. To calculate the number of Animal Units available on the Preserve, I needed to complete a grazing survey. My sampling method entailed collecting forage from multiple square-foot sites at each of the Preserve’s ten dominant soil formations, then extrapolating their weights to estimate a grand Animal Unit total. The forage samples I collected were cut an inch above the ground to allow for regrowth – an example is pictured below. My thirty samples are currently drying, will be weighed next week, and then I’ll be able to complete the calculations that will deliver the carrying capacities of all different kinds of livestock based on Animal Units.

Stay posted,


One square-foot forage sample

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