Environmental aspects of pasture management

  • By Steve Boyles OSU Beef Extension Specialist
  • April 28, 2011
  • 335
                        
Ohio has a USDA-ARS research station where agricultural practices can be studied for their impact on soil erosion, surface water, and groundwater quality. The following information is from a factsheet provided by Lloyd B. Owens, Research Soil Scientist, USDA-ARS North Appalachian Experimental Watershed, Coshocton. Soil Loss: Pasture systems that are not overgrazed, either unimproved or improved, will be within soil loss tolerance limits. Pasture systems are good systems for controlling soil loss and sediment entering streams, ponds and reservoirs. Practices that will help reduce or prevent the potential for soil loss are: 1. Fencing livestock away from streams 2. Using limited rotation of a herd during winter feeding as contrasted with constant occupancy in a small pasture Surface Runoff: The most likely times for high NO3-N (nitrate-nitrogen) and PO4-P (phosphate-phosphorus) concentrations to occur in runoff are within a few days following fertilizer application. Therefore, fertilizer applications should not be made on saturated soils and/or when runoff is likely to occur within the next few days. Phosphorous fertilizer should be applied to pastures in response to soil tests (not just routinely applied). Unimproved pastures, if not overgrazed, usually have surface runoff water quality similar to or better than ungrazed wooded areas. Subsurface Flow: In fertilized pastures, much more nitrogen (N) will be lost in the groundwater than in surface runoff. Most of the subsurface N loss occurs during the late winter/early spring when forages are dormant. It can take several years to see the full impact of surface management practices on groundwater quality. Groundwater NO3-N concentrations will remain acceptable if N application levels do not exceed 100-pounds per acre annually taking into account manure, purchased fertilizer, and legume contributions (also hay that has been brought in for feed). Another strategy is to use legumes as the primary source of N for pastures with N fertilization restricted to strategic applications to overcome summer slump or to stockpile in the autumn.


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