THE EFFECT OF LIVESTOCK GRAZING ON SURFACE RUNOFF AND SOIL-EROSION FROM SLOPING PASTURE LANDS IN THE ETHIOPIAN HIGHLANDS

Effects of livestock grazing on surface runoff and soil erosion at var ying slopes were studied in pasture lands within Ginchi watershed, Eth iopia. The results showed that livestock grazing in the watershed foll owed distinct seasonal and spatial patterns. During the rainy season, grazing pressure was greatest on the upper slopes (>5% slope) while th e pressure shifted to the lower slopes during part of the dry season. Seasonal grazing pressure in different parts of the watershed was furt her complicated by the fact that during the rainy season and immediate ly after the rains, grazing was limited to individually designated pas ture lands while during most part of the dry season, the entire waters hed became a common grazing resource for livestock of watershed reside nts as well as those farmers outside the watershed. It was observed th at, on pastures above 4.2% slope, there is the risk of erosion rates e xceeding the estimated soil loss tolerable limit under the current gra zing pressures (heavy grazing), while slopes exceeding 5.8% are likely to suffer soil erosion under moderate grazing pressure at the current level of biomass productivity. Since livestock are mobile, farmers te nd to take advantage of this attribute by seasonally moving the livest ock to different parts of the watershed. This study has demonstrated t he need for better understanding of the resource use patterns beyond t he individual farmlands, most preferably at watershed level, so that o n-site and off-site effects of seasonal concentration of livestock can be incorporated into developing feed production and management strate gies for improving the system productivity and environmental protectio n.