Jatropha curcas l. For rehabilitation of Degraded land of gilgel gibe watershed, south Western Ethiopia

Abstract

Decline in soil fertility has become a serious problem affecting all spheres of social, economic and political life of the Ethiopia population. This problem is continuing and natural resource base is deteriorating at alarming rate. As the result agricultural productivity has been declined from years to years. Some tree/shrubs species are integrated to the farming system to rehabilitate degraded land. One of such Species which are commonly integrated with farming system is Jatropha. Therefore, the study was conducted to assess the role of Jatropha curcas to rehabilitate soil fertility. In order to achieve the objective, Melka Leku sub watershed from the Gilgel Gibe catchment was selected from south western Ethiopia. Soil samples were collected by using stratified sampling method at depth of 0-30cm from land with Jatropha and adjacent land without Jatropha plant. For each land use, sites were divided into three slope categories; at each slope three replicates were used. The result of the study shown that, all selected soil physicchemical properties (texture, BD, MC, pH, EC, OC, OM, TN, AvP, CEC, basic cations and PBS) measured under land with Jatropha was significantly different (p< 0.05) from land without Jatropha. Soils under land with Jatropha were superior for all selected soil fertility indicators than adjacent land without Jatropha except BD, sand and silt fractions. The mean values of soil clay, pH, OM, TN and AvP of land with Jatropha and adjacent land without Jatropha site were 54.44 and 37.67%, 6.58 and 5.67, 6.91 and 3.17%, 0.41 and 0.27%, and 18.93 and 14.18 ppm, respectively. Moreover, land use interaction with slope positions had a significance (p< 0.05) difference for all measured soil parameters except for bulk density and silt fractions. These mean values soil properties (except BD and silt) under land with Jatropha of slope position on upper area were significantly (p< 0.05) lower than foot slope positions of the same land use type. While topographic position and nature of the land also contribute to enhance soil fertility, Jatropha plantation has promising potential to play a decisive role on rehabilitating degraded soil fertility of the study area