Ground Cover Impacts on Sediment and Phosphorus Export from Manured Riparian Pasture

• Published in: Journal of environmental quality 2006-11, Vol.35 (6), p.2178-2185
• Main Authors: Butler, D.M, Franklin, D.H, Ranells, N.N, Poore, M.H, Green, J.T. Jr
• Format: Article
• Language: English
• Subjects: agricultural runoff; Agronomy. Soil science and plant productions; Animal Husbandry; Animals; Applied sciences; Aquatic ecosystems; beef cattle; Biodegradation, Environmental; Biological and medical sciences; Bos taurus; Cattle; compacted soils; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Environmental degradation; Exact sciences and technology; feces; Festuca - growth & development; Festuca arundinacea; forage grasses; Freshwater; Fundamental and applied biological sciences. Psychology; Geologic Sediments; grassland soils; Grasslands; grazing; Ground cover; ground cover plants; Height; Losses; Manure; nonpoint source pollution; North Carolina; Paspalum dilatatum; Pasture; pastures; phosphorus; Phosphorus - analysis; Phosphorus - metabolism; Pollution; pollution load; Pollution, environment geology; Rain; rainfall simulation; riparian areas; Runoff volume; Sandy loam; sandy loam soils; Sandy soils; sediment yield; Sediments; Simulated rainfall; Soil Pollutants - analysis; Soil Pollutants - metabolism; Soils; Studies; Surface water; Urine; vegetation cover; water pollution; water quality
• ISSN: 0047-2425; 1537-2537
• DOI: 10.2134/jeq2005.0351

Maintaining pasture ground cover is important in preventing environmental degradation of grasslands and associated riparian areas. The objective of this work was to determine the effect of ground cover on sediment and P export from pastured riparian areas under simulated rainfall events. Plots were established on two sites in the North Carolina Piedmont: a 10% slope with Appling sandy loam soils (fine, kaolinitic, thermic Typic Kanhapludults) and a 20% slope with Wedowee sandy loam soils (fine, kaolinitic, thermic Typic Kanhapludults), both with mixed tall fescue (Festuca arundinacea Schreb.)-dallisgrass (Paspalum dilatatum Poir.) vegetation. Existing forage stands were modified to represent a range of ground cover levels: 0, 45, 70, and 95% (bare ground, low, medium, and high cover, respectively), and amended with beef steer (Bos taurus) feces and urine (about 10 kg P ha-1). Mean runoff volume from bare ground was generally twice that observed from low, medium, and high levels of cover, which were similar. For all rainfall events combined, export of dissolved reactive P was greatest (P < 0.1) at bare ground and was reduced 31% at low cover, which did not differ from medium or high cover. Mean total Kjeldahl P export was greater (P < 0.001) from bare ground than from other cover levels. Results indicate that riparian bare areas can contribute substantial sediment (>215 kg ha-1) and P (0.7 kg P ha-1) to surface waters during heavy rainfall, whereas export may be reduced equally well by low cover (45%) as by high cover.