ABSTRACT
Phosphorus is a key nutrient element required for optimum levels and sustain productivity as it limits plant growth in many soils. This study investigated phosphorus sorption kinetics in Alagba soil series of Nigeria Institute for Oil Palm Research (NIFOR), Benin City, Edo State.
The study was conducted on soil samples collected from four (4) soil depths (0 -30, 30 -60, 60-90, 90 -120 cm) in 3 replicates from Alagba soil series field thirty-seven (37), the samples were prepared and analyzed for some soil physical and chemical properties using standard method. The phosphorus sorption kinetics capacity was determined by equilibrating 3g soil in 50 mg/L P solution at various equilibrating time (5, 30, 60, 180, 900 and 1800 minutes) using a reciprocating mechanical shaker, the P concentration was developed by sulphuric-molybdate after equilibration and the difference between the quantity of P (50 mg L-1) added to the soil and the quantity of P in solution after shaking with soil was calculated as the quantity of P sorbed by the soil in milligram per kilogram. The data obtained from phosphorus sorption kinetics experiment was fitted to pseudo-second order, intra-particle diffusion and elovich kinetic models. Genstat statistical package was employed for data analysis while Duncan multiple range was used to separate means at P <0.05.
The results showed that the amount of P adsorbed varied across the soil depth with the different equilibrating time. The P adsorbed at 5, 30, 60, 180, 900 and 1800 minutes had a mean value of 9.33, 16.4, 10.5, 27.9, 27.0 and 33.5 mg kg-1 respectively. The P adsorbed was least at the soil surface (0-30 cm) across all the equilibrating time. Considering the goodness of fit (R2), The pseudo-second order showed superiority over intra-particle diffusion and elovich model with a mean R2 value of 0.9719.
