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Chemical water quality of runoff from grazing land in Nebraska: I. Influence of grazing livestock

Schepers, J.S., Francis, D.D.
Journal of environmental quality 1982 v.11 no.3 pp. 351
water quality, agricultural runoff, hydrochemistry, water analysis, grazing, pastures, total solids, chemical oxygen demand, carbon, nitrogen, nitrate nitrogen, ammonium nitrogen, wildlife, biodegradation, plant litter, nutrients, nonpoint source pollution, water pollution, sediments, Nebraska
The chemical quality of runoff water from a 32.5-ha cow-calf pasture area at the Roman L. Hruska U.S. Meat Animal Research Center near Clay Center, Nebr., was determined over a 3-year period. Runoff events from the grazed pasture were separated into those occurring while livestock were grazing and those occurring when no livestock were present. Grazing livestock increased by 52% the total solids concentration, but only increased total organic carbon and chemical oxygen demand concentrations by 11 and 7%, respectively, and decreased by 19% the total Kjeldahl nitrogen concentration. Concentrations of NH4-N, NO3-N, total P, soluble P, and Cl- were 6, 45, 37, 48, and 78% greater, respectively, when livestock were grazing. Runoff from an ungrazed control area within the pasture contained chemical concentrations that ranged from 1.94 to 10.8 times greater than those from an adjacent pasture under ungrazed conditions. We attributed these elevated concentrations to wildlife activity and decomposition of plant material.