Evaluation of some Conventional methods for Estimating Available Phosphate in Muds at Mbiabet Rice Farm, Akwa Ibom State

Abstract

A study was carried out in May 2008 using Seven Conventional methods for estimating available soil phosphorus from swamp mud, in acid sulphate soils of Mbiabet, Akwa Ibom State, Nigeria. The Seven extractants were tested to determine which would be suitable for routine use in the water-logged soils. The extractans were Bray and Kurtz’s (0.03NNH₄F in 0.025N Hcl), Morgan’s (10% NaOAC/3%HOAC), Sounder’s (0.1NNOOH), Olsens (0.5N NaHCO₃ at pH 8.5). Treatment consisted of potassium dihydroxide added in the doses of 0, 50, 100, 150, 200, 250 and 300mg/kg, fitted into Latin square of 36 x 5m. Limestone (Ca CO₃) was applied at the rate of 50 kg/ha to reduce the activity of aluminum. The results of the selective tests showed that the Oslen’s procedure gave the most reliable estimate of available P. Fractionation of the forms of inorganic phosphorus in the phosphate treated mud showed that the extracting solutions removed chiefly aluminium phosphate. In the absence of facilities for field, the relationship between crop response, concentration of soil phosphorus and available phosphorus as determined by Olsen’s procedure gave the most reliable estimate of available P. was estimated for polyethylene bag culture experiment with rice and maize. Response to additions (Rice and Maize) had available P 11 mg/kg with Oslen’s method.