CHARACTERIZATION AND CLASSIFICATION OF SOILS OF HATE LEMAN MICRO-WATERSHED IN DUGDA DISTRICT, CENTRAL ETHIOPIA

Abstract

Site specific soil studies that include survey, characterization and classification at large scale are necessary to identify the production potentials and constraints that may limit agricultural Production and thereby to make site specific appropriate recommendations to solve agricultural problems based on the spatial variability of soil properties. The present study was conducted with the objective of characterization, classification and mapping soils of Hate Leman micro-watershed in Dugda District, Central Ethiopia. Detailed soil survey was conducted and three pedons were opened along topographic positions (at shoulder, back and foot slope), described in field and sampled. A total of 28 soil samples, 14 disturbed and 14 undisturbed were taken from identified genetic horizons for laboratory analysis. The results revealed variation in the morphological, physical and chemical characteristics of the soils, which led to the general assessment of the fertility status of the soils and the identification of different diagnostic soil characteristics (diagnostic horizons, properties and materials) used for the soil classification. Accordingly, the soils of the present study area were generally found to have high to very high base status but free of salinity hazard, and had a range of pH value suitable for the production of most crops (pH of 6.4 – 7.6), especially in their upper two layers (0 – 60 cm) that encompass the main root zone, which indicated their remarkable chemical fertility. However, almost all the soils had low to very low ratings of total nitrogen and available phosphorus, which may denote the likelihood of nitrogen and phosphorus deficiency that needs consideration in the fertility management aspects of the soils of the study area. Furthermore, all the pedons had sandy loam (SL) to sandy clay loam (SCL) textural classes and were free of internal drainage problems had granular soil aggregates and friable moist consistence in their surface layers. Based on the field survey and soil analytical results ,soil characterization and the subsequent classification activities resulted in the identification of the diagnostic soil characteristics that enabled the categorization of the soils to the RSGs of the World Reference Base for Soil Resources were done, where by chernic surface horizon, calcic subsurface horizon and calcaric material were identified in all the pedons; and a protocalcic property was additionally detected in the profiles of the pedons opened at the back-slope (P1) and foot-slope (P2) positions. Accordingly, P1 and P2, were classified as Hypocalcic Chernozems(Hypereutric, Humic, Panto loamic) , and pedon3, which was opened at the upper slope position was classified as Chernic Endo-hypocalcic Phaeozem (Hypereutric, Humic, Panto-loamic).The soils sampled in the study area were categorized only to two reference soil groups, namely, the Chernozems and Phaeozems, that have many characteristics in common, which might have been primarily due to the smallness of the study area that contributed to the relative homogeneity of soils.