Abstract:
To determine the soil's primary potentials and constraints, soil characterization and
pedological classification are crucial. However, much of Ethiopia’s documented soil
information is scanty and inadequate relative to the large size of the country and the wide
diversity of soils and landscapes. The aim of this work was to characterize and classify the
morphological, physical, and chemical attributes of soils in Aregedif watershed,
Northwestern Ethiopia. Samples were collected from genetic horizons of representative soil
profiles to study the morphological and physicochemical characteristics and to classify the
soils of the Aregedif watershed, Northwestern Ethiopia. Reconnaissance survey and extensive
auger observations (70 points) of the research area were made. Seven representative pedons
(2×2×1 m) were opened and described in situ, at a slope of 0-2%,2-5%, 5-10%, 10-15%, and
>15%. Seventeen distributed and undisturbed soil samples were collected. Most soil profiles
have a depth of >150cm deep and some of them are less than 150cm. Most profiles have
granular and subangular blocky structures and textural classes vary from sandy to clayey.
The surface bulk density values varied between 1.2 to 1.44 g/cm
-3
and the total porosity was
between 43 to 55%. The organic carbon content of the soil ranged between low to medium
(0.5 -1.83%) and very low to medium (0.09-1.37%) at the surface and subsurface horizons,
respectively. The total nitrogen content of the soil ranges from very low (0.04%) to moderate
(0.2%) at the surface and subsurface horizon, respectively. Available phosphorous content
ranged from 3.74 (low) to 8.86mg kg
-1
(high) at the surface horizon and decreased down the
depth. The cation exchange capacity of the soil was medium (18.8_cmol (+) kg
) to high
(37.8_cmol (+) kg
-1
) for all surface and subsurface horizons. Base saturation also ranged
from medium to very high on both surface and subsurface horizons. The soils were found to
have low to medium Zn and Cu and moderate to high Fe and Mn contents. Four soil types
(Rhodic Luvisol and Pellic Vertisol (0-2%) (Profile 2 & 4), Chromic Vertisol (2-5%) (Profile
7), Vertic Luvisol and Rhodic Nitisol (5-10%), (Profile 1 & 5), Eutric Leptosol (10-15%)
(Profile 3), and Skeletic Leptosol (>15%) (Profile 6) were identified based on the
classification of world reference base, 2022 in the Aregedif watershed. The varying properties
and types of soils identified in the study areas provide adequate information to design soil
management options and further study should focus on soil landscape - land management
relationships for the sustainable use of the land.