EFFECT OF SCATTERED MORINGA STENOPETALA (BAK.F.) CUF TREES ON SELECTED SOIL PHYSICOCHEMICAL PROPERTIES AND ZEA MAYS L. GRAIN YIELD AT KARFURA MICRO-WATERSHED, SOUTHERN ETHIOPIA

Abstract

Watershed degradation in Ethiopia has become major environmental threat and caused significant damages to the natural environment. Biological measures are an effective and cheap method of soil and water conservation with woody and non woody tree species. Moringa stenopetala is a deciduous multipurpose tree usually planted in agroforestry systems of southern Ethiopia. The current study was conducted to evaluate the effects of scattered M. stenopetala (Bak.F.) Cuf trees on selected soil physicochemical properties and Zea mays L. grain yield at Karfura micro-watershed, southern Ethiopia. Totally, 36 soil samples from the depth of 0-20 cm were collected in four directions at three radial distances (1 m, 3 m and 10 m) from M. stenopetala tree trunks and samples from the same radial distances were bulked together for soil physicochemical properties analysis. Also a total of 36 maize grain yield samples were collected from plots laid 1 m*1 m in four directions of the selected tree trunks at three radial distances, and samples from the same radial distances were composited and weighed by using digital balance for analysis. Means between radial distances analysed by one way ANOVA and interaction between radial distances and elevations were analysed by two-way ANOVA. The mean separation was done using confidence interval of 5%. The study results showed that the soil textural class for both high and low altitude areas was clay loam, while that for the mid-altitude was silt loam. The soil bulk density values increased significantly (p<0.05) with increasing distance from tree trunk while the reverse happened for moisture content. The contents of Total Nitrogen (TN) and Available Phosphorus (AP) were high under the tree canopy and significantly declined with increasing distances from the tree trunk. Even though it was not significant, numerically maize grain yield, Organic Carbon (OC) and Electrical Conductivity (EC) under tree canopy were high compared to the open bare land. Total nitrogen, available phosphorus, organic carbon, electrical conductivity and maize grain yield were significantly different (p<0.01) along the altitude but their values were decreasing with increasing altitude. Also as the altitude get increased, the value of moisture content did show a significantly (p<0.05) decreasing trend. The present finding farther suggest that incorporating M. stenopetala trees with cereal crops like maize is important in maintaining the soil fertility and improving the grain yield of associated crops under similaragro -ecological condition