Using Eucalyptus for Soil & Water Conservation on the highland Vertisols of Ethiopia

Resource degradation is a critical problem in the highlands of Ethiopia. With agricultural productivity lingering behind population growth the gap between the availability and the demand for agricultural land continues to grow. This results in severe land-use conflicts. Thus, high potential and more resilient soils need intensification to sustain human needs. This thesis discusses the opportunities of a short rotation (3 years) eucalyptus based agroforestry system to intensify annual sole cropping on the highland Vertisols. This soil type represents a major production resource in this agroecosystem but is vastly underutilized due to severe waterlogging. A typical Vertisols-Nitosolstoposequence in Ginchi watershed in the central highlands of Ethiopia was selected for this study. The productive and protective functions, alternative resource utilization, the farm economics and the allelopathic potential of anEucalyptus globulusagroforestry system were investigated. The proposed agroforestry system increases land productivity, cuts down soil erosion rates to tolerable limits, reduces runoff, and increase the proportion of available water for biomass production without inducing significant nutrient depletion. Eucalyptus trees capture part of the runoff and soil which otherwise get lost for agricultural crops. This justifies their integration into sole cropping systems thereby compensating for the extra resource required for their growth. Therefore, the farmers' choice to plant Eucalyptus species on seasonally waterlogged highland Vertisols must be acknowledged by policy makersIt is unthinkable to get other species, be it indigenous or exotic that can substitute Eucalyptus in a full range of benefits it provides on highland VertisolsA presumed allelopathic effect of eucalyptus has little ecological relevance and the role of Eucalyptus is far reaching when it is evaluated in its potential contribution to the substitution of dung. Under appropriate management practices dung