Inputs and Losses by Surface Runoff and Subsurface Leaching for Pastures Managed by Continuous or Rotational Stocking
- L. B. Owens *a,
- D. J. Barkerb,
- S. C. Loerchc,
- M. J. Shipitaloa,
- J. V. Bontaa and
- R. M. Sulcb
- a USDA–ARS, P.O. Box 488, Coshocton, OH 43812
b The Ohio State Univ., Dep. of Horticulture and Crop Science, 2021 Coffey Rd., Columbus, OH 43210
c The Ohio State Univ., Dep. of Animal Sciences, OARDC, Wooster, OH 44691. Salary and research support provided in part by state and federal funds appropriated to the Ohio Agric. Res. and Dev. Ctr. (OARDC) and The Ohio State Univ. Partial financial support was also provided by the National Research Initiative of the USDA Cooperative State Research, Education and Extension Service (now National Inst. for Food and Agriculture), grant number 2006-55618-17025. Assigned to Associate Editor Jim Miller
Pasture management practices can affect forage quality and production, animal health and production, and surface and groundwater quality. In a 5-yr study conducted at the North Appalachian Experimental Watershed near Coshocton, Ohio, we compared the effects of two contrasting grazing methods on surface and subsurface water quantity and quality. Four pastures, each including a small, instrumented watershed (0.51–1.09 ha) for surface runoff measurements and a developed spring for subsurface flow collection, received 112 kg N ha−1 yr−1 and were grazed at similar stocking rates (1.8–1.9 cows ha−1). Two pastures were continuously stocked; two were subdivided so that they were grazed with frequent rotational stocking (5–6 times weekly). In the preceding 5 yr, these pastures received 112 kg N ha−1 yr−1 after several years of 0 N fertilizer and were grazed with weekly rotational stocking. Surface runoff losses of N were minimal. During these two periods, some years had precipitation up to 50% greater than the long-term average, which increased subsurface flow and NO3–N transport. Average annual NO3–N transported in subsurface flow from the four watersheds during the two 5-yr periods ranged from 11.3 to 22.7 kg N ha−1, which was similar to or less than the mineral-N received in precipitation. Flow and transport variations were greater among seasons than among watersheds. Flow-weighted seasonal NO3–N concentrations in subsurface flow did not exceed 7 mg L−1. Variations in NO3–N leached from pastures were primarily due to variable precipitation rather than the effects of continuous, weekly rotational, or frequent rotational stocking practices. This suggests that there was no difference among these grazing practices in terms of NO3–N leaching.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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