Characterization of Soil of Jijiga Plain in the Somali Regional State of Ethiopia

Keywords: Available phosphorus; Cation exchange capacity; Soil organic carbon; Soil organic matter; Soil texture; Soil pH


October 10, 2018


Abstract: Low soil fertility and poor soil fertility management practices constrain crop production in
Ethiopia. Diagnosing soil fertility problems and characterizing soils are a prerequisite for formulating
appropriate soil fertility management practices. However, most soil fertility problems in Ethiopia are
not diagnosed, and the soils are not characterized. This invariably leads to lack of documented
information for judicious application of soil ameliorative measures to increase crop yields. This study
was, therefore, aimed at characterizing soil of Jijiga Plain in the Somali Regional State of Ethiopia on
which wheat is commonly grown. The study was conducted during the main cropping season of
2012/2013. The study area was stratified in to three altitude categories 1650 - 1700, 1750 - 1800, 1850
- 1900 meters above sea level prior to sampling. Then, a total of 3 x 2 x 30 x 3 = 540 disturbed soil
samples were collected from the surface (0-15 cm) and subsurface (15-30 cm) layers across the altitude
categories. The samples were composited treatment-wise to 3 x 6 = 18 sub-samples. The composite
soil sub-samples were analyzed for selected soil physico-chemical properties. The data were analyzed
using descriptive statistics. The results indicated that both the surface and subsurface soils are clayey
in texture. The pH of the soil at the layer of 0 - 30 cm ranged from 8.37 to 8.82 and is rated as
strongly alkaline. The exchangeable Ca2+ contents of the soil at the surface and subsurface soil layers
were 24.52 and 30.52 cmol+/kg, respectively, which is rated as very high in both soil layers; the
exchangeable Mg2+ content is 7.36 cmol+/kg in the surface soil layer, which is rated as high, but 10.21
cmol+/kg in the sub-surface soil layers, which is rated as very high. The exchangeable Na+ content of
the soil ranges from 0.33 to 2.16 cmol+/kg, which is rated as medium to high. The exchangeable K+
contents of the surface and subsurface soil layers are 1.1 and 1.4 cmol+/kg, respectively, which are
rated as high and very high in the surface and sub-surface soil layers. The cation exchange capacity of
the soil ranges from 37.17 to 40.49 cmol+/kg, which is rated as high to very high. The percent base
saturation in the surface soil is 89.63% whereas that in the sub-surface soil is 109.23%, which is rated
as very high. The contents of soil organic carbon (1.81%) and total nitrogen (0.13%) in the surface
soil layer were found to be medium whereas those of the sub-surface soil layer were found to be low.
However, the available phosphorus contents of both the surface (2.4 mg kg-1 soil) and sub-surface
(1.87 mg kg-1 soil) soil layers were found to be very low. It could, thus, be concluded that, the soil of
the study area is characterized by strong alkalinity with high contents soluble calcium carbonate, very
low content of plant-available phosphorus, and medium contents of soil organic matter as well as total
nitrogen. However, the texture and other chemical properties of the soil do not appear to limit crop
production. Therefore, there is a need to take ameliorative measures aimed at lowering the pH and
increasing availability of soil phosphorus, soil organic carbon, and total nitrogen to improve wheat
and other crop yields in the study area.

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