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
