Impact of Elevation Change on the Physicochemical Properties of Forest Soil in South Omo Zone, Southern Ethiopia

Abstract

The assessment of the distribution of soil physicochemical properties provides basic information for our understanding of the soils to grow crops and sustain forests and grasslands. The changes in soil physicochemical properties along elevational gradients were studied in a less accessible Sida Forest, southern Ethiopia. Hence, the present study was conducted to assess the distribution of soil physicochemical properties along the elevational gradients and to evaluate the fertility status of the soil. Data on soil physicochemical properties were collected from five points (four from each corner and one from the center) of the main plot. A pit of 20 cm × 20 cm was dug at a depth of 0–30 cm and a kilogram of composite soil samples was brought to the Wolkite Soil Testing Laboratory for physicochemical analysis. The results revealed that the physicochemical properties of the collected soil samples show a significant correlation with elevation changes. Sand had a significantly negative correlation and variation with elevation; it decreases as elevation increases with the rate of correlation (r = −0.44 ${}^{\ast \ast }$ , $P\le 0.001$ ). However, silt had a nonsignificantly positive (r = 0.20, $P<0.079$ ) correlation to the elevation, while clay had a significantly positive correlation to elevation, and it increases as elevation increases with the rate of correlation coefficient (r = 0.40 ${}^{\ast \ast }$ , $P\le 0.001$ ). Soil OC, OM, TN, CEC, and exchangeable Mg2+ had significant positive correlation to the elevation; they increase as elevation increases with the rate of correlation coefficient (r = 0.42 ${}^{\ast \ast }$ , $P\le 0.001$ ), (r = 0.41 ${}^{\ast \ast }$ , $P\le 0.001$ ), (r = 0.44 ${}^{\ast \ast }$ , $P\le 0.001$ ), (r = 0.34 ${}^{\ast \ast }$ , $P<0.002$ ), and (r = 0.27 ${}^{\ast }$ , $P<0.014$ ), respectively. While BD, pH, EC, Av. P, exchangeable Ca2+, and exchangeable K+ had a nonsignificant negative correlation to the elevation, they decrease as elevation increases with the rate of correlation (r = −0.70 ${}^{\ast \ast }$ , $P<0.134$ ), (r = −0.20, $P<0.075$ ), (r = −0.05, $P<0.683$ ), (r = −0.04, $P<0.701$ ), (r = −0.04, $P<0.693$ ), and (r = −0.053, $P<0.693$ ), respectively. This study attempted to provide information on the impact of elevation on soil’s physicochemical properties. Given that, the soil’s physicochemical properties exhibit variation with elevation changes.