Soil Quality Attributes Induced by Land Use Changes in the Fincha’a Watershed, Nile Basin of Western Ethiopia

Abstract

The success of soil management to maintain soil quality depends on an understanding of how soils respond to land use and practices over time. As a result, the important soil quality indicators were investigated under two land use systems to provide base line data for future research in the Fincha’a Valley Sugar Estate (FVSE), within the Nile basin of Western Ethiopia. The evidences provided by this study indicated that land use changes caused ^{changes on soil bulk density (ρ}b^{), soil water content, Particle size distribution (sand, silt and} clay), soil pH, electrical conductivity (EC), soil organic matter (SOM), total N, carbon to nitrogen ratio (C:N) and available phosphorous (Av. P). The study revealed that soil organic matter (SOM), sand content and total N decreased with increase in soil depth. While bulk density (ρb), EC and clay content increased with soil depth. Particle size distribution (sand, silt, and clay) varied with land use, soil depth and soil type. Particle size distribution was ^{changed from Sandy clay to clay due to land use change. Bulk density (ρ}b^{), EC, soil organic} matter (SOM) and C:N varied significantly (P<0.01, P<0.05), respectively, with land use and soil depth. Land use changes caused bulk density (ρb) to be increased. The study indicated that soil pH was higher in irrigated land than the un irrigated land. This attributed to the transportation of soluble cations from the upstream to the downstream irrigated land by water soil erosion. The different soil fertility management practices also contributed to the variation. On the other hands, soil organic matter (SOM) and total N were lower in irrigated land. Relatively, the lower soil organic matter (SOM) and total N contents in irrigated land attributed to the optimum soil moisture content throughout the year that created favorable environmental condition for SOM decomposition. The study also revealed that soil management groups and soil water holding capacity at field capacity and permanent wilting point were affected by irrigation (land use).It was identified more than 50% of the soil quality indicators increased with depth. This might be the influence of irrigation water in accelerating leaching process. The main degradation process overcome the study area was waterlogging and soil compaction. The irrigation development in the area requires improved drainage network and proper land management. Therefore, reducing the intensive mechanized tillage practices and use of integrated inorganic and organic fertilizers could replenish the degraded soil quality for sustainable agricultural production in the study area. It is therefore, suggested that appropriate and integrated land management options for different land use systems together with identification of soil management groups and water retention characteristic curves are required to sustain agricultural productivity while protecting the environmental degradation.