At her experimental plots on the Flying M Ranch, Roberts spent a year measuring the soil carbon, which includes roots, fungus, bacteria, microscopic organisms and mycorrhiza, at each of the nine plots. What she found was that the intensively grazed plots did indeed have a higher amount of carbon per gram of soil. Over a year of measurements, the carbon content was 11 percent higher than plots that weren’t grazed at all.

Johnson explained that one hypothesis is that when cows munch the plant shoots above ground, it causes a dieback of roots, which delivers organic carbon deeper into the soil that may then decompose more slowly. Another hypothesis is that the cattle’s hooves push the plant pieces deeper into the soil.

“The key factor for increasing carbon storage below ground is to make the inputs of dead plants greater than the decomposer organisms can break down the compounds and respire out CO2,” Johnson wrote in a follow up email.

At the same time, Savory’s grazing method proved to have some drawbacks. The experiments found an increase in invasive species and noxious weeds on the heavily grazed land. Soil compaction also rose, which changes the ability for the water to filter into the ground and created drier soils, Roberts said.