Hydrologic response of selected grazing systems on the Edwards Plateau

Abstract

This study was conducted on the Sonora Agricultural Research Station, located on the Edwards Plateau. Study objectives were to: (1) determine the hydrologic response of a range site under very heavy continuous (EXT), high intensity low frequency (HILF), and moderate continuous (MC) grazing systems; and (2) determine the influence of these livestock grazing systems on vegetation and soil parameters. Infiltration rates and sediment production were determined with a drip type infiltrometer on shortgrass and midgrass interspace in each grazing treatment ten times during the 18-month study period. Soil and vegetation variables evaluated were bulk density, soil moisture, surface roughness, organic matter, aggregate stability, forb and grass standing crop, and mulch accumulation. Cover of bare ground, rock, mulch, forbs, midgrasses and shortgrasses was also determined. Infiltration rates were reduced and sediment production increased by the EXT treatment after only two months of treatment. The MC and HILF treatments exhibited little difference in infiltration rates or sediment production. Differences in sediment production due to very heavy grazing of midgrass interspace appeared after five months of treatment, while differences on the shortgrass interspace occurred after only two months of treatment. ...