Submitted to: Proceedings of the National Conference on Grazing Lands
Publication Type: Proceedings
Publication Acceptance Date: 12/13/2009
Publication Date: 4/1/2010
Citation: Sanderson, M.A., Feldmann, C., Schmidt, J.P., Herrmann, A., Taube, F. 2010. Occurrence and distribution of livestock concentration areas on intensively managed pastures. In: Proceedings of the 4th National Grazing Conference. Society for Range Management. 279-283. Interpretive Summary: An interpretive summary is not required.
Technical Abstract: Livestock frequently congregate at feeders, shades, or other sites on pastures creating point sources of nutrient runoff. Our objective was to determine the spatial distribution of soil nutrients in livestock concentration areas on pastures and quantify the relationships among the soil nutrient gradients, vegetation, and surface runoff. We located and measured all concentration areas on five farms (four grazing dairies and a beef farm) during 2 yr. Selected areas were sampled to 0-2 and 0-6 inch depths to determine soil nutrient levels compared with unaffected areas of the pasture. On two farms, we selected three concentration areas for intensive soil sampling (20 to 25 samples to a 2-inch depth distributed on each of five variable-length transects) to examine the spatial distribution of soil nutrients. On one farm we installed runoff plots at three landscape positions on two concentration areas to examine nutrient losses in surface water runoff from simulated rainfall. Concentration areas associated with paddock gates were the largest in number, whereas feed areas (e.g., hay and mineral feeders, sacrifice feeding paddocks) accounted for the most pasture area affected by livestock concentration. Soil nutrient levels were usually higher in concentration areas than unaffected areas of the pasture; however, there were some important exceptions where concentration areas had lower soil nutrient levels. Most of the concentration areas were small, isolated from water bodies, and surrounded by vegetation, which would buffer them from surface runoff losses of nutrients. These areas seemed to pose little threat to water quality but create greater spatial variation in soil properties. Sacrifice paddocks used for winter feeding or other purposes had extreme levels of soil P and direct connections to water courses, which were a direct threat to water quality.