Longterm Grazing Density Impacts on Soil Compaction

Livestock activity can modify soil properties by degrading soil structure, increasing soil bulk density, and reducinginfiltration rate. Impacts of grazing on soil compaction were studied on rangeland in the tallgrass prairie region ofOklahoma. Rotational grazing treatments included low (12.5 cows/ha), medium (25 cows/ha), and high (50 cows/ha) stockingdensities with ungrazed pastures used as control sites. Soil compaction was assessed 10 years after grazing treatments wereinstalled using penetration resistance, bulk density, and rate of water infiltration. Longterm livestock grazing increasedresistance to penetration and bulk density values, but only in the upper 10 cm. The surface infiltration rate decreased from28.5 cm/day for the ungrazed treatment to 7 cm/day under light grazing, 5 cm/day under moderate stocking, and 5 cm/dayfor the heavily grazed treatment. Longterm grazing impacts were restricted to the soil surface, thus increasing the potentialsoil loss due to erosion.The reduced rainfall infiltration caused by compaction suggests that less water is available for plantuse.