Phosphorus was measured using Bray I method [23]. Bray 1 solution was added to compost and soil samples and shaken vigorously for 1 min. The resulting solution was centrifuged at 6000 rpm for 5 mins. The supernatant was dispensed into a colourimetric tube; Reagent C was added and resulting solution determined for phosphorus using the UV/visible Spectrophotometer (Jenway Model 6405).
The percent organic matter was calculated by multiplying the value of organic carbon by 1.729 based on the assumption that organic matter contains 58% organic carbon (i.e., % Organic Matter = % Organic Carbon × 1.729) (http://soilquality.org/indicators/total_organic_carbon.html).