Titration Curves of Soil Organic Matter

Abstract

IN a previous paper¹ it was claimed that the addition of small amounts of copper sulphate to a suspension of acid-washed organic matter resulted in the release of two hydrogen ions for each of added copper. This release was detected by titration of portions of the organic matter with alkali in the presence and absence of copper (ref. 1, Fig. 5). Further experiments with organic matter extracts of peats and podzols have not confirmed a general proton release of this magnitude and are in conformity with the results of Martin and Reeve². These authors revealed new complications in such experiments, in particular the important association of aluminium with soil organic matter and the difficulty of removing this metal. The purpose of this note is to correct the inaccuracy in my earlier paper and to add further information on the ability of soil organic matter to complex transition metals.