LAND USE EFFECTS ON SOIL ORGANIC CARBON AND NITROGEN IN SOME SOILS OF BALE, SOUTHEASTERN ETHIOPIA

Agricultural and economic growth in Ethiopia are constrained by the deteriorating natural resource base, especially in the highlands where 80% of the population lives. This threat stems from the depletion and degradation of the vegetation cover of the country, especially forests and unsustainable farming practices. This study investigated the effects of different land-uses on soil organic carbon and total nitrogen. Both, soil organic carbon (SOC) and total nitrogen (TN) were responsive to land use change. Considering the top 0-5 cm depth, the highest SOC (12.95%) and TN (0.8%) were recorded in natural forest while the least, 2.56 and 0.21%, respectively from cultivated lands. The lowest SOC content in cultivated soils could be due to reduced inputs of organic matter and frequent tillage which encouraged oxidation of organic matter. SOC and TN consistently declined with increasing soil depth in all land use systems. The SOC and TN content calls for restoration of soil organic matter through sustainable soil management