DETERMINATION OF TOTAL ORGANIC PHOSPHORUS IN SOILS BY EXTRACTION METHODS

Abstract

Comparisons were made between the quantities of organic phosphorus extracted from some Alberta soils by the Kaila-Virtanen method (10), an expanded Kaila-Virtanen procedure, and the Mehta et al. method (15). The modifications for the Kaila-Virtanen method were introduced as a result of the present study.One of the main difficulties encountered in the expanded procedure was the selection of organic solvents that would not interfere with the molybdophosphoric blue color reaction. The non-interfering acetone and acetone containing 0.2 M acetyl acetone gave increased extraction of organic phosphorus from the surface and B horizon samples, respectively. Hydrofluoric acid was recommended for B horizon samples.The expanded Kaila-Virtanen procedure extracted significantly more organic phosphorus (at 5 per cent level) than either of the other methods. The expanded Kaila-Virtanen method does not require more analytical time than the original. Furthermore, as a result of a larger number of extractions involved, this expanded procedure should have an advantage over the other two for studying the various forms of organic phosphorus extracted.