Ziziphus spina-christi is a multipurpose tree which grows naturally on the farm lands in Habru district. Since, the effects of this tree on soil and crop have not scientifically quantified; this study has been carried out with the aim of assessing the effect of Ziziphus spina-christi on soil physicochemical properties, grain and biomass yield of sorghum.Five isolated and nearly identical Ziziphus spina-christi tree growing on farm lands with similar site condition were selected and canopy coverage of each tree was divided into four radial transects. Soil samples from three horizontal distances: 1.2m, 2.9m and 15m with two soil depths (0–15cm and 15-30cm) were taken for analysis of soil physico- chemical properties. Three quadrates 1m x1m at each transect and distances were laid for sorghum grain yield and biomass estimation. The result shows that soil pH, EC, CEC and soil texture were not significantly (p>0.05) influenced by Ziziphus spina-christi tree, whereas soil bulk density, soil moisture content, total nitrogen, organic carbon, available phosphorus and exchangeable cation (Mg, Ca and K) were significantly (P<0.05) influenced mainly due to higher organic matter input through litter fall, root biomass, uptake and return of nutrients from deeper soil profiles under the tree canopies. While the grain yield of sorghum and above ground biomass were not statistically significant (p>0.05).Hence, retaining of this tree on crop land improves the soil fertility status.

Over 90% of the energy consumed in the country depends on woody biomass. The rising demand for tree products and expanding population pressure resulted in decline of forest cover and consequently the demand for tree products exceeded the supply. This study was conducted at Armania Kebele with the aim of to evaluate different cutting time and management practices yielding more wood biomass volume. One indigenous tree species, preferable by the farmers, namely Acacia nilotica was selected and the experiment design in 3x4 factorial experiment with randomized complete block design arrangement and replicated three wise. Eight trees per plot were planted in two rows with 2 meter spacing. The result shows that, Acacia nilotica could be coppiced well with 13 to 29 numbers of coppices per stump at all stages of cutting time. Root collar diameter and plant height were highly correlated with growth period. Hence, Leaving of two and three number of coppices could give higher woody biomass volumes as compare to leaving one and all number of coppices and control (uncut). Therefore, it is necessary that farmers should allow two and three number coppice per stump to get high woody biomass volume for fuel-wood consumption.