keywords: Characterization, classification, Edo state, landuse, parent materials
Soils systematic arrangement into groups or categories on the basis of their characteristics has become imperative in view of the ever increasing need for the soil-with particular reference to sustainable landuse. Soils of Edo state Nigeria were characterized with a view to understanding its intricate properties and classify it using the United States department of agriculture (USDA) soil taxonomy and correlated with the world reference base (WRB). A free survey technique was used in identifying soil mapping units under different parent materials using the Edo state geological and mineral map. Pedons 1, 2 and 3 were marked as Ekpoma, Benin and Okpella soils respectively. Pedon 1 is derived from clayey sands, pedon 2 from sands and pedon 3 from shale and mudstones. Results showed that in all the three different parent materials sandy and loamy sands were the dominant textural classes. Pedon 3 was found to have more sand followed by pedon 2 and pedon 1, respectively. The C/N ratios in all the profile showed the trend similar to that of OC. Ca and Mg were found to range from very low to low in pedon 1 and 2 and moderate in pedon 3. The available phosphorus did not follow any regular pattern but decreased down the profiles. Total exchangeable acidity (TEA) was lowest in pedon 3(0.05 cmol/kg) and highest in pedon 1(1.12 cmol/kg).the effective cation exchange capacity (ECEC) of the soils were critically low, an indication that these soils requires amendment for crop production. The percentage base saturation has relatively high mean values 67.48, 55.50 and 97.68% for pedons 1, 2 and 3 respectively and the LDS showed significant difference among the three different parent materials. There were positive correlations between the soil pH and OC, CN, available phosphorus, TEB (Ca, Mg, K, Na). pedons 1 and 2 were classified as Alfisols (Isohyperthermic Psammentic Arennic Hapludalfs) while pedon 3 was classified as typic kandiustalfs. The landuse potential in Edo state under these different materials is high provided integrated soil fertility management practice is put in place.
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