Nitrogen, phosphorus and organic carbon in streams draining two grazed catchments

摘要: High concentrations of N, P and organic C in water cause problems such as excessive eutrophication reservoirs bacterial growth distribution systems. The aim this study was to measure the export streams draining two grazed catchments with no point sources Mt. Lofty Ranges, South Australia, during 1 yr. Retreat Valley catchment (1.3 km2) is by sheep, has steep topography, loam over clay soils. Lawless (3.0 flatter, dairy cattle, sand Rainfall specific runoff were similar. Annual exports 924 kg suspended solids, ha-1, 9.0 N 1.0 55 ha-1 from Valley; 40 6.6 1.1 66 Lawless. In Valley, 33% 86% 65% particulate forms resulting erosion, 45% nitrate. Lawless, 82% 76% 92% dissolved. Of dissolved approximately 93% organic. Concentrations both streams, exceeded desirable limits. A combination management options, including grazing fertilizer application, soil amendment, subsurface drainage, could lead reductions nutrient loads.