Phosphorus forms in soils of Oban Hills, Akamkpa, Cross River State, Nigeria

Abstract

Oban Hills is located at Akamkpa in the Southern Senatorial District of Cross River, State, Nigeria. Phosphorus (P)-rich soil from the Hills is expected to have an effect on retention and distribution in the highly acidic soils surrounding the area inundated for several years. Phosphorus forms in the soils of the Hills varied with the year of deposition with the highest fraction being Ca-P. The low soil pH in the Oban Hills soils suggests that Ca-P may exist in a partially dissolved form and will be the primary source of P for vegetations around the area. The cation exchange capacity and pH of surface material from the Hills suggest a dominance of primary minerals. Based on the amount of P available it seems that the Hills soils play a role in the overall P availability to the surrounding vegetation. A significant (P<O.05) decrease in HCI soluble P with depth was observed in the OB2 soil site, where the greatest amount of HCI-soluble P was found in the 0-15cm soil depth. The bicarbonate P varied with sites (OBI, OB2 and 0B3), and depth, but the OB3 had the highest value.