EFFECT OF FAIDHERBIA ALBIDA AND CORDIA AFRICANA TREE SPEC IES ON SOIL PHYSICOCHEMICAL PROPERTIES IN BAKA DAWLA ARI DISTRICT, SOUTH OMO ZONE, SOUTHERN ETHIOPIA

Abstract

Information concerning about the effects of tree species on soil properties in Ethiopia is very limited to be of use for improved agricultural productivity. Trees on farms make easy the nutrient cycling in the soil; enrich the soil with nutrients and organic matter and improving soil structure. It is clear that a lot of tree species enhance the fertility of the soil beneath their canopy. The aims of the study were to evaluate the effects of Faidherbia albida and Cordia africana tree species on selected soil physicochemical properties under and outside the canopy of the tree and at varying soil depths. Randomized complete block design was used to determine the effect of trees on soil physiochemical properties. A total of thirty six composite soil samples were taken at 2.5 m, 5 m and 25 m radial distances from the base of each selected Faidherbia albida and C.africana trees in four dimensions from surface (0- 20 cm) and subsurface (20-40 cm) soil layer and their physiochemical properties were analyzed in soil laboratory. The data were analyzed using two way ANOVA following general linear model of SAS statistical method. The result revealed that soil texture was not influenced by the tree species (p>0.05). Soil bulk density was significantly (p<0.05) lower under canopy of trees than open field and in surface soil than in subsurface soil. As well as soil moisture content was significantly (p<0.05) higher under canopy of trees than open field. Soil chemical properties (EC, pH, CEC, SOC, TN, Av.P, exchangeable Ca, exchangeable Mg, exchangeable Na and exchangeable K) were significantly (p<0.05) higher under canopy than open field and in surface than subsurface soil. It can be concluded that these tree species have the potential to improve soil fertility and moisture beneath their canopy. Thus, retaining and planting of these tree species in particular Faidherbia albida on crop field is recommended. The N and K amount of soils under and away the canopy of both tree species were in line with the recommended range for optimum growth of most crops while P concentration was rated low for optimal crop growth. Due to the deficient levels of soil P, sustainable crop production in the district requires supplementary application of P fertilizers