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

Abstract: Low soil fertility and poor soil fertility management practices constrain crop production inEthiopia. Diagnosing soil fertility problems and characterizing soils are a prerequisite for formulatingappropriate soil fertility management practices. However, most soil fertility problems in Ethiopia arenot diagnosed, and the soils are not characterized. This invariably leads to lack of documentedinformation for judicious application of soil ameliorative measures to increase crop yields. This studywas, therefore, aimed at characterizing soil of Jijiga Plain in the Somali Regional State of Ethiopia onwhich wheat is commonly grown. The study was conducted during the main cropping season of2012/2013. 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 soilsamples were collected from the surface (0-15 cm) and subsurface (15-30 cm) layers across the altitudecategories. The samples were composited treatment-wise to 3 x 6 = 18 sub-samples. The compositesoil sub-samples were analyzed for selected soil physico-chemical properties. The data were analyzedusing descriptive statistics. The results indicated that both the surface and subsurface soils are clayeyin texture. The pH of the soil at the layer of 0 - 30 cm ranged from 8.37 to 8.82 and is rated asstrongly alkaline. The exchangeable Ca2+ contents of the soil at the surface and subsurface soil layerswere 24.52 and 30.52 cmol+/kg, respectively, which is rated as very high in both soil layers; theexchangeable Mg2+ content is 7.36 cmol+/kg in the surface soil layer, which is rated as high, but 10.21cmol+/kg in the sub-surface soil layers, which is rated as very high. The exchangeable Na+ content ofthe 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 arerated as high and very high in the surface and sub-surface soil layers. The cation exchange capacity ofthe soil ranges from 37.17 to 40.49 cmol+/kg, which is rated as high to very high. The percent basesaturation in the surface soil is 89.63% whereas that in the sub-surface soil is 109.23%, which is ratedas very high. The contents of soil organic carbon (1.81%) and total nitrogen (0.13%) in the surfacesoil 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 ofthe study area is characterized by strong alkalinity with high contents soluble calcium carbonate, verylow content of plant-available phosphorus, and medium contents of soil organic matter as well as totalnitrogen. However, the texture and other chemical properties of the soil do not appear to limit cropproduction. Therefore, there is a need to take ameliorative measures aimed at lowering the pH andincreasing availability of soil phosphorus, soil organic carbon, and total nitrogen to improve wheatand other crop yields in the study area.