Mob Grazing Carbon: 0.5-1.2 tC/ha/yr vs. Zero Under Continuous Grazing

The Numbers

Mob-grazed pastures in temperate climates accumulate soil carbon at 0.5-1.2 tC/ha/yr in the top 30 cm, compared to 0-0.2 tC/ha/yr under continuous set-stocking in comparable conditions. This 4-6x difference is documented in Stanley et al. (2018, Agricultural Systems 162:249-258), corroborated by Savory Institute soil monitoring data (2015-2022), and further supported by the Rodale Farming Systems Trial long-term data. See also the grazing carbon math cluster page for the full mechanism stack and soil testing protocol detail.

The White Oak Pastures Life Cycle Assessment by Quantis (2019) documented net carbon sequestration of 3.5 tC/ha/yr across their regenerative grazing operation in Bluffton, Georgia. That rate is higher than the Stanley et al. temperate numbers because of subtropical biomass production rates and multi-species livestock stacking. The general validity of the mechanism is consistent across both datasets; the absolute magnitude scales with climate and biomass productivity.

The Mechanism

Mob grazing concentrates animal impact temporally. 200-400 cattle move across a small paddock for 4-24 hours, then move on. The grass is bitten once, trampled, urinated on, and dunged on. Then the paddock rests for 60-120 days. The rest period is the driver of carbon accumulation. During rest, grass roots regrow deeply, mycorrhizal networks repair and expand, and the hoof-pressed organic matter layer integrates into the topsoil. Continuous set-stocking has no rest period and no concentrated impact event, so root turnover is suppressed and organic matter input is diffuse across a permanently grazed sward. The management variable, not the presence of cattle, is the causal factor in the carbon difference.

The additionality objection, that the soil would have sequestered carbon regardless, fails against the trial data. The Stanley et al. control plots under continuous grazing did not accumulate significant soil carbon. The mob-grazed treatments on comparable paddocks did. The grazing management is the variable that changed, and it is the variable that explains the difference.

The Scale Implication

A 100-hectare mob-grazed operation banks approximately 50-120 tC/yr versus 0-20 tC/yr under continuous grazing. At carbon credit prices of 30-80 EUR per tCO2e (approximately 110-290 EUR per tonne of carbon at the 44/12 CO2-to-C conversion), the revenue gap between management systems runs 5,000-35,000 EUR per year for a 100-hectare operation. This is before counting pasture yield improvement, biodiversity uplift, or drought resilience gains, all of which have measurable economic value independent of carbon pricing. The carbon revenue is an additional income stream layered on top of the production gains from improved pasture condition. For the full operations case, see the Gabe Brown case study dispatch and the pillar essay on rotational grazing.