The case for a soil benefit
Well-managed, rotational grazing can contribute to soil health in a few documented ways: hoof action can help break up surface crusting and work plant litter into the soil surface, manure returns nutrients and organic matter directly to the ground being grazed, and grazing that's timed to avoid overuse can stimulate root growth in some grass species, similar to how mowing encourages denser turf.
Some rangeland studies have found modest increases in soil organic matter under well-managed rotational grazing compared to unmanaged or overgrazed land, particularly on grassland systems studied over multi-year periods.
Where the strongest claims overreach
Some popular claims — that grazing alone can meaningfully offset agricultural greenhouse gas emissions at scale, for instance — go well beyond what the current research base actually supports; the science on grazing's soil-carbon impact is genuinely mixed, varies enormously by climate, soil type, and grazing management, and remains an active area of research rather than settled fact.
For a short-duration targeted-grazing project on brush or fuel reduction — as opposed to season-long ranching operations that most of this research actually studies — soil-health effects are a modest secondary benefit at best, not the primary reason to hire a herd. The primary, well-supported case for targeted grazing remains vegetation and fuel-load reduction; soil benefits are real in some contexts but shouldn't be oversold.