Characteristics of Soils Types along the Toposequence in Central Highlands of Ethiopia

It is imperative to understand and predict the nature and distribution of soils along a given physiographic condition. However, the hitherto practices of collecting basic soil information at a site-specific level seem inadequate to ensure sustainable agricultural production via proper utilization and effective management of soil resources. Therefore, this research was conducted to characterize, classify, and map soils along the toposequence of the Qenberenaweti sub-watershed, Central Highlands of Ethiopia. A total of 91 auger inspections were made up to a 120 cm depth to define soil mapping units with their boundaries. Then, six pedons were opened at typical slope positions along the toposequence. The depth of the pedons varied between 135 and 200+ cm, whereas the thickness of A-horizons showed an increasing trend down the slope by excluding the back-slope position. All the soils at the surface and subsurface horizons had clayey texture with pH ranging from 5.59 to 6.23 and 5.31 to 7.65, respectively. The OC contents throughout the entire horizons varied from 0.22 to 2.03%. The highest CEC values were found at the middle slope position followed by pedons at the upper and bottom parts. The exchangeable cations of most pedons were in declining order of Ca, Mg, K, and Na except for the Mg dominance over Ca at the back slope and bottom depression. Hereby, six soil types were identified; and their distribution was mapped. The results of this research revealed that the extent of variations in key topographic features resulted in the formation, development, and distribution of diversified soils along the toposequence. Consequently, such detailed soil characterization, classification, and mapping work is vital for proper planning, management, and utilization of the soil resources at local topographic conditions. However, further research should be done to ensure sustainable agricultural production in the study area.