Soil Fertility Characterization in Vertisols of Southern Tigray, Ethiopia

Abstract

A fresh soil profile pit was opened and representative soil samples were collected from the profile and surface (0-15 cm) soil of the experimental area to characterize the fertility status of the soils of the study area on the base of selected physicochemical properties. The soil textural class of the surface layer (0-25 cm) of the profile and the mean composite surface (0-15 cm) soil samples of the experimental field was clay loam while it was clay for the subsurface (25-150+ cm) layers of the profile. The bulk density values of the layers in the profile varied consistently with depth ranging from 1.18 g cm-3 at the surface layer to 1.32 g cm-3 at the bottom layer while the average bulk densities of experimental field. The bulk and particle density values increased consistently with depth of the profile ranging from 1.18 to 1.32 and 2.51 to 2.85 g cm-3, respectively. The organic matter (0.05 to 4.39%), available P (0.86 to 22.50 mg kg-1) and total N (0.03 to 0.23%) of the soil profile decreased consistently with depth. Both the profile and the composite surface soil sample indicated that the soil of the site was slightly acidic to moderately alkaline in reaction (6.5 to 8.20). The soil exchange complex was mainly dominated by Ca and Mg where the order of occurrence was Ca > Mg >K > Na. The CEC values were very high ranging from 41.42 to 50.37 c mol (+) kg-1. The results of the study revealed that the physical and chemical properties of the soils are highly variable to each other which disagrees the blanket rate of fertilizer recommendation throughout the country. The turning point to solve the problems should be restoring, maintaining and increasing the fertility status of the soils. These phenomena necessitate soil-crop specific fertilizer recommendation. Therefore, the existing soil fertility problems should be addressed sooner by introducing/developing resistant crop varieties, applying organic and inorganic fertilizers, and other soil fertility management options.