In most developing countries, particularly in Ethiopia, there is declining soil fertility and limited use of inorganic fertilizers due to poverty and limited subsidies for inorganic fertilizer use. Thus, integration of soil fertility improving tree species in farming systems remains a plausible option to sustaining soil productivity.Because, nutrient release from the tree leaf fall is believed to be the major factor for the transferring of nutrients and energy from living biological components to the soil and contribute to the soil fertility and its associated productivity. In this case, a good understanding of the contribution of locally available tree species requires information on the litter production, and nutrient release and cycling processes. However, so far little is known on the effects of many of the locally growing soil fertility improving tree species on to soil chemical and nutrient contents and are still lacking. This book is therefore helpful as a basis for determining appropriate soil fertility management strategies and soil productivity.