Defoliation by Sheep‐Grazing Versus Mower‐Clipping for Evaluation of Pasture 1

Yields within three grass species and two alfalfa varieties defoliated by sheep‐grazing or machine‐clipping were nearly identical in a year of limited moisture. With adequate moisture, grazing caused higher yields of all forages, until extremely high levels of N (for grasses) and K (for alfalfa and grasses) were applied to both treatments. Sheep excreta significantly increased K levels of soil and plant tissue. Comparable heights of defoliation by the two methods left twice as much residual leaf and stem tissue after grazing, but this did not increase subsequent forage yields. Significantly more weeds invaded clipped plots in late summer. Regrowth of sod cores in darkness at the end of each season indicated more total reserves per unit area under grazing due to more tillers and roots per unit area. However, no differences in grams of top growth per gram of stubble and root appeared under the two methods of defoliation.