Summary: This paper from 2010 is a compilation of previous studies on grazing lands and carbon drawdown which themselves date from the 1990s. It shows that grazing lands/rangelands are major stores of terrestrial carbon, occupying approximately 3.6 billion hectares and accounting for about one-fourth of potential carbon (C) sequestration in world soils. Drawdown rates via grazing and on restored semi-arid savanna are reported to be as high as 2.75 tons per hectare per year.
Follett, Ronald F., and Debbie A. Reed. 2010. “Soil Carbon Sequestration in Grazing Lands: Societal Benefits and Policy Implications.” Rangeland Ecology & Management 63 (1):4-15.