Farmington, Georgia

Agriculture, Ecosystems and Environment 129 (2009) 28-36 reports that a 12-year study by the Agricultural Research Service (Alan Franzluebbers) showed significant gains in soil organic carbon under continuous season-long grazing of a Bermuda grass pasture with a stocking rate of 5.8 500-lb. steers per hectare (14.3 per acre).

Some pastures were fertilized with inorganic nitrogen, others with broiler litter. Soil organic carbon concentrations were greatest within 5 meters of shade and water. Ungrazed, unharvested pasture plots gained .64 tons C per hectare per year, those with high grazing pressure (8.7 steers per hectare) .51 tons C per hectare per year, and hayed plots lost .22 tons C per hectare per year. Below 30 cm depth, soil carbon losses over the 12-year study period were common.