Mob Grazing Effects On Pasture Utilization and Nutrient Deposition in South Dakota.

Ranchers are highly motivated to shift to more productive grazing systems because of increasing feed costs and loss of pastureland production. Mob grazing, or ultra high stocking densities in rotational grazing, is hypothesized to increase harvest efficiency and herbage production as the aboveground portions of plants are either recycled as manure or urine or trampled into the ground by the hooves of grazing animals.  However, to date, no research has quantified vegetation utilization and manure deposition in mob versus more traditional rotational grazing systems in northern Great Plains’ rangelands.  We sampled vegetation and manure deposits within quadrats along transects before and after grazing at 9 producer sites in South Dakota.   Producers are located across a gradient of drier, low producing sites in the west to more productive, wet regions in the east and demonstrate a wide range of stocking densities.    This variability allowed us to examine mob grazing effects on harvest efficiency and nutrient return across different climates and management methods.  We found that more forage was utilized in mob systems than traditional rotational grazing irrespective of location and stocking densities.  We also observed greater manure deposition in mob-grazed sites.  Results suggest that mob grazing can increase harvest efficiency and nutrient deposition in northern Great Plains’ pastures.  Greater pasture utilization and production will allow increased stocking rates, greater profitability for livestock producers, and promote grassland sustainability.