Assessment of Soil Acidity and Fertility Status under Different Land Uses Types in Sayo District of Western Ethiopia

Abstract

Assessing the status of surface soil acidity under various land-use types on selected soil physicochemical properties is useful to tackle the expansion of soil acidity and mitigate its side effects in agro-ecosystems for the sustainable management of soil resources. As a result, this study was carried out to evaluate the status of soil acidity under different land use types in the Sayo District of Western Ethiopia. A total of 24 composite soil samples were collected from natural forest, cultivated land, grazing land and eucalyptus tree plantation landfrom the surface (0–20 cm) with three replications. Analysis of variance was used to test the mean differences in soil physicochemical properties under different land use types. Accordingly, sand and clay mean values were highest in cultivated and grazing land, respectively, whereas the lowest values were registered under grazing and cultivated land respectively. The lowest (0.93 cm^–3) mean values of bulk density registered under natural forest land and the highest (1.50 cm^–3) mean values recorded under eucalyptus tree plantation land, conversely the lowest (40.11%) and highest (55.99%) mean values of total porosity observed under eucalyptus tree plantation and natural forest land respectively. In the case of soil chemical properties, the highest (3.07) and lowest (0.47) mean values of the exchangeable acidity were observed under cultivated and grazing land respectively and the highest (35.10%) and lowest (3.26%) mean values of AS persentage were recorded under cultivated and grazing land respectively. The lowest (4.99) and highest (5.62) mean soil pH were observed under cultivated and grazing land respectively whereas the lowest (1.81%) and highest (7.94%) mean values of OM registered under cultivated and natural forest land respectively. the lowest (0.12%) and highest (0.47%) mean values of total N observed under eucalyptus tree plantation and natural forest land respectively while the lowest (3.35 mg/kg) and highest (11.95 mg/kg) mean value of available P registered under cultivated and grazing land respectively. Moreover the higher mean values of exchangeable bases, CEC and PBS were recorded under grazing and natural forest land whereas the lower recorded under cultivated and eucalyptus tree plantation land. Conversely, the higher mean values of extracted micronutrients were registered under cultivated and eucalyptus tree plantation land while the lower recorded were under grazing and natural forest land. Generally, the conversion of land use from natural states exaggerates the surface soil acidity of the study sites. Particularly, the cultivation of deforested land and grasslands reduces the soil pH which results in high total exchangeable acidity and acid saturation. The status of essential plant nutrients such as total nitrogen, available P, exchangeable cations and SOM (source of most nutrients) follows the trends of soil pH which results in the decline of soil productivity. Thus, sustainable soil ecosystem management is very essential to mitigate land degradations that result particularly for reduce agricultural production.