Impact of land cover changes and topography on soil quality in the Kasso catchment, Bale Mountains of southeastern Ethiopia
Singapore Journal of Tropical Geography
Department of Geography, Madawalabu University, Bale, Ethiopia; Department of Geography, University of South Africa, Gauteng, South Africa; Geography and Environmental Studies, Addis Ababa University, Addis Ababa, Ethiopia
This study assessed land cover change and topographic elevation on selected soil quality parameters in the Kasso catchment, southeastern Ethiopia. Twenty-seven soil samples collected from 0-30cm depth under four land cover types across three elevation gradients were analysed for selected soil quality parameters. Results indicated that soil particle size distribution is different (p<0.001) in the catchment because of the effect of land cover change and elevation. Most cultivated lands occupy lower elevations where clay accumulates as a result of its movement from higher to lower elevations. Ploughing accentuates weathering, making cultivated lands richer in finer materials. Cation exchange capacity and exchangeable magnesium and potassium negatively correlated with elevation, total nitrogen and available phosphorous. Conversion of natural vegetation to cropland contributed to changes in pH (p<0.05), exchangeable calcium (p<0.01), potassium (p<0.001), available phosphorous (p<0.01) and nitrogen (p<0.01) contents. Parameter soil degradation index results showed that soil organic carbon, nitrogen, available phosphorous and exchangeable potassium contents declined and bulk density increased because of the land cover change. This negative effect on agricultural development and environmental health of the catchment makes an integrated land resource management approach indispensable for sustaining agricultural productivity and the environmental health of the Kasso catchment. © 2015 Department of Geography, National University of Singapore and Wiley Publishing Asia Pty Ltd.
cation exchange capacity; erosion rate; land cover; particle size; plowing; size distribution; soil degradation; soil erosion; soil quality; spatial variation; topographic effect; vegetation dynamics; Bale Mountains; Ethiopia