QUANTIFICATION OF PHOSPHORUS FRACTIONS IN SOIL SOLUTION

Various chemical treatments and analytical procedures have been used t o quantify inorganic and organic fractions of the total phosphorus pre sent in soil solution. Molybdate reactive PO43- (the fraction most com monly used to specify soluble P) accounted for less than 30% of the to tal P in solution collected from a highly organic upland soil. Substan tial amounts of organically associated and non reactive P compounds we re also present. Soil solutions obtained by centrifugation contained u p to 30 times more total P than when extracted in situ by suction cup lysimeters.