Effects of land-use-cover-changes on selected soil physicochemical properties along slope position, Coka watershed, Southern Ethiopia

Land-use changes along slope position can have a major positive or negative impact on soil environment and agricultural productivity. Relevant information to understand the negative effect of land-use change and slope variability on soil property is a vital element to monitor, plan and make the decision to improve productivity and restore the environment. The aim was to examine the effects of land-use-cover-changes along slope position on the selected soil physicochemical properties in the Coka watershed. Soil samples were gathered from 5 nearby land uses, namely forestland, grassland, bushland, cultivated land, and bare-land, and 3 slope positions (upper, middle, and lower slope) at 0–30 cm soil-depth, analyzed in Hawassa University Soil testing laboratory. The results show that the highest field capacity, available water-holding, porosity, silt, nitrogen, pH-value, cation exchange capacity, sodium, magnesium, and calcium were in forestlands and lower-slope. The highest water-permanent-wilting-point, organic-carbon, soil-organic-matter, and potassium were in bushland; bulk density was in bare land while the highest clay and available-phosphorus were revealed in cultivated land and lower slope. Most soil properties showed a positive correlation with each other except bulk density which has a negative correlation with all soil properties. Generally, cultivated land and bare land have the least concentration in most soil properties which indicates of increasing degradation rate in the area. Thus, soil-organic-matter and other yield-limiting nutrients should be improved in cultivated land to maximize productivity by using an integrated implementation of soil fertility management through cover crops and rotation, compost, manures, and minimum tillage; and amending soil pH-value by liming.