RELATIONSHIP BETWEEN P SORPTION AND SOIL PROPERTIES IN SOILS DERIVED FROM BASEMENT COMPLEX AND SEDIMENTARY PARENT MATERIALS

This study was conducted to determine the different forms of Phosphorus and the impact of soil properties on the Phosphorus fixing capacity of soils overlying the basement complex and sedimentary parent materials of Oyo and Ogun States in Nigeria respectively. The experiment was an incubation study which lasted a period of five weeks. Five representative top soil (0 – 15 cm) samples and five sub-surface soil (15 – 30 cm) samples were collected from five different locations in each of Oyo and Ogun States. This study was a factorial combination of the 20 soil samples, three rates of single superphosphate (SSP) fertilizer. (0, 30 and 60) kg/ha with three replications laid out in completely randomized design (CRD). All the soils studied experienced desorption. In the soils derived from sedimentary parent materials, the Fe and Al sesquioxides both accounted for over 50% of the soil P fractions. Also for soils derived from basement complex, the Fe and Al sesquioxides both accounted for over 70% of the soil P fractions. Correlation analysis revealed that soil pH was the major soil property influencing sorption of P (r = -0.49, P < 1%) followed by the soil age Feo/ Fed (r = 0.40, P < 5%) for soils derived from basement complex. For soils derived from sedimentary parent materials, correlation analysis revealed that Ammonium Oxalate extractable Alo (r = 0.54, P < 1%) dithionite-citrate-bicarbonate (DCB) extractable Ald (r = 0.49, P < 1%) and crystalline Al (r = 0.39, P < 5%) are dominant factors influencing P sorption.