grams of air dried soil was transferred into a
250 ml shaking bottle and 50 ml of Olsen‟s
extracting solution (0.5M NaHCO3, pH 8.5) was
added to each bottle to achieve a 1:20 soil to
extractant ratio. The extraction was achieved by
shaking the mixture on an electrical shaker for 30
minutes. The suspension was then filtered
through Whatman no. 42 filter paper.
Phosphorous concentration in the filtrate was
determined colorimetricaly by the ascorbic acid
method at 880 nm using a UV –VIS
Spectrophotometer (Jenway).