Impact of Topography on Soil Properties in Delboatwaro Subwatershed, Southern Ethiopia

Abstract

Soil characterization and classification are prerequisites for better agricultural productivity and sustainable soil fertility management. This study was previously conducted to characterize and classify DelboAtwaro, a watershed in southern Ethiopia. Three pedons classes were inspected and three representative pits (pedons) opened, i.e. one in each pedon. Pedons were described in accordance with FAO [1] and WRB (2014) in the study area, and then soil samples were collected from recognized horizons of each pedon and analyzed for selected physicochemical properties. The pedons confirmed the variability of the physical, chemical and morphological properties of the soils in the study area. Based on the result of field and laboratory soil analysis, the soil structure was early clay in both aboveground and subterranean strata. The soil chemical reaction used to be somewhat acidic to neutral in reaction (pH 6.1-7.0). The organic carbon (OC) content varied between 1.23 and 1.78% between the respective topographical positions. The cationexchange capacity (CEC) of the soils ranged from 39.8 to 79.9 cmol (+) kg-1 (intermediate to optimal), while the percent base saturation (PBS) ranged from 23.7 to 40.7%. The dominance of the exchangeable bases was once, in descending order, Ca>Mg>K>Na. Soils ranged from low to optimal in TN and very low to low in available P, while the concentrations of micronutrients in the soils were best (Fe), very high (Mn), adequate (Zn), and optimum (Cu). The soil had a molly epipedon with humic diagnostic houses in the subsurface. Hence the soil was categorized as Rhodic Nitisols (Haplic) (US, MS, and LS) according to the WRB for soil resources. In general, slope and land use influenced soil properties in the different topographical locations of the Delbo Atwaro Underwater Catchment, suggesting the need for integrated soil fertility management to sustainably conserve soil organic matter and nutrients.