Long-term effects of grazing management and buffer strips on soil erosion from pastures

Authors: PILON, CRISTIANE - University Of Arkansas; Moore, Philip; Pote, Daniel; PENNINGTON, JOHN - Beaver Watershed Alliance; Martin, Jerry; Brauer, David; RAPER, RANDY - Oklahoma State University; Dabney, Seth; LEE, JOHN - Natural Resources Conservation Service (NRCS, USDA)

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/20/2016
Publication Date: 3/17/2017
Citation: Pilon, C., Moore Jr, P.A., Pote, D.H., Pennington, J.H., Martin, J.W., Brauer, D.K., Raper, R.L., Dabney, S.M., Lee, J. 2017. Long-term effects of grazing management and buffer strips on soil erosion from pastures. Journal of Environmental Quality. 46(2):364-372. doi:10.2134/jeq2016.09.0378.

Interpretive Summary: Cattle grazing increases runoff and subsequent soil erosion in pastures. However, the addition of buffer strips at the edge of field may reduce nutrients and sediment loads from fields to waterways. The goal of this long-term study was to evaluate the impact of grazing management strategies and buffer strips on soil erosion by assessing soil physical properties, hydrology, sediment loads and forage growth from pastures fertilized with broiler litter. This field research was conducted for 12 years on 15 small watersheds. During this period, five management strategies were evaluated; hayed (H), continuously grazed (CG), rotationally grazed (R), rotationally grazed with a buffer strip (RB), and rotationally grazed with a fenced riparian buffer (RBR). Broiler litter was applied each year at a rate of 5.6 Mg ha-1. Bulk density and penetration resistance increased as grazing pressure increased and was highest for continuously grazed watersheds. Runoff volumes, sediment concentrations and sediment loads were lower for hayed watersheds and watersheds that were rotationally grazed with fenced riparian buffers, although values varied over the years. Annual sediment losses at the edge of field increased as runoff increased. Both observed sediment load and that predicted by RUSLE2 indicated that the continuously grazed treatment promoted higher erosion, and fenced riparian buffer strips maintained low erosion in rotational grazing pasture, although RUSLE2 overpredicted sediment loss from CG and H systems. Percent cover and forage production were inversely related to grazing pressure, with hayed watersheds resulting in the highest yields. Converting a pasture to a hay field or utilizing rotational grazing in conjunction with a fenced riparian buffer appear to be the best options for reducing soil erosion and runoff to waterways.

Technical Abstract: High grazing pressure can lead to soil erosion in pastures by compacting soil and increasing runoff and sediment delivery to waterways. Limited information exists on the effects of grazing management and best management practices (BMPs), such as buffer strips, on soil erosion from pastures. The objectives of this research were to evaluate the impact of grazing management strategies and buffer strips on soil erosion by assessing soil physical properties, hydrology, sediment loads and forage growth from pastures fertilized with broiler litter. Field studies were conducted for 12 years on 15 small watersheds. During this period, five management strategies were evaluated; hayed (H), continuously grazed (CG), rotationally grazed (R), rotationally grazed with a buffer strip (RB), and rotationally grazed with a fenced riparian buffer (RBR). Broiler litter was applied each year at a rate of 5.6 Mg ha-1. Bulk density and penetration resistance increased as grazing pressure increased and was highest for continuously grazed watersheds. Runoff volumes, sediment concentrations and sediment loads were lower for hayed watersheds and watersheds that were rotationally grazed with fenced riparian buffers, although values varied over the years. Annual sediment losses at the edge of field increased as runoff increased. Both observed sediment load and that predicted by RUSLE2 indicated that the continuously grazed treatment promoted higher erosion, and fenced riparian buffer strips maintained low erosion in rotational grazing pasture, although RUSLE2 overpredicted sediment loss from CG and H systems. Percent cover and forage production were inversely related to grazing pressure, with hayed watersheds resulting in the highest yields. Converting a pasture to a hay field or utilizing rotational grazing in conjunction with a fenced riparian buffer appear to be the best options for reducing soil erosion and runoff to waterways.