5 years ago

Die Wirksamkeit von Boden

Die Wirksamkeit von Boden

SCRP Soil Conservation

SCRP Soil Conservation Research Program of Ethiopian SPSS Statistical Package for Social Sciences SSA Sub-Saharan African SWC Soil and Water Conservation TLU Tropical Livestock Unit TN Total Nitrogen UN United Nations UNCCD United Nations Convention to Combat Desertification UNESCO United Nations Educational Scientific and Cultural Organization Up Upper-landscape Position ZEF Zentrum für Entwicklungsforschung (Center for Development Research)

1 GENERAL INTRODUCTION General introduction 1.1 Background and problem statement Land degradation is a serious global environmental problem. However, wide disparity exists on the extent, depth, type and drivers of the problem (Stocking and Murnaghan 2000; FAO 2004; FRA 2005). A global assessment of human-induced soil degradation (GLASOD) indicated that globally about 560 million hectares (36% of total) of farmlands had degraded at an annual rate of 5 to 6 million hectares (Scherr 1999). Land degradation is severe in developing countries, particularly in Africa, where almost all inhabited lands in Sub-Sahara Africa (SSA) are prone to soil and environmental degradation (Nana-Sinkam 1995; Scherr 1999; FAO 2004; Vlek et al. 2008). Similarly, the natural resource and land degradation in Ethiopia is exceedingly high (Hurni 1993; Shiferaw and Holden 1999). The Ethiopian highlands are most vulnerable to the land degradation problems (Shiferaw and Holden 1999; Dubale 2001). For example, annual deforestation was estimated at about 160,000 to 200,000 hectares (EFAP 1994), and the annual fertile topsoil lost at about 42 t ha -1 on crop lands but may also reach up to 300 t ha -1 in individual fields (Hurni 1993). Land degradation has a long history in the northern highlands, which were settled 5000 years ago (Hurni 1987; El-Swaify 1997). Wello is one of the highland areas in northern central Ethiopia that is severely affected by land degradation (Woldesemait 1983; Tekle 1999). Carbon dating showed that forest burning in Wello began over 2460 years ago, which indicates a long history of resources degradation (Hurni 1987). Resources over-exploitation and inappropriate land use such as over-grazing, deforestation, expansion of cultivation and grazing into marginal lands, and backward agricultural practices are considered as the major causes of land degradation (Nana- Sinkam 1995; Stocking and Murnaghan 2000; FAO 2004; FRA 2005). The major driver in Ethiopia is conversion of forest and marginal lands into agriculture due to the growing population pressure together with inappropriate agricultural practices. The Ethiopian population has been growing at a fast rate from 12 million at the beginning of the 1900s to 74 million in 2007, i.e., at a rate of

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