Improvements in colorimetric determinations

Summary

• 1. The paper describes a rapid method for estimation of organic carbon by photo-electric colorimeter which has distinct advantages over Walkley and Black’s wet combustion method. In the procedure followed, the change of colour from Chromate yellow to chromic green in oxidation of organic matter by dichromate and sulphuric acid, has been made use of for colour standardization and estimation of organic carbon in soils.

• 2. A simple method suitable as field technique (R.C.M.) has also been evolved on the same principle and tested on a large number of soils of different organic carbon concentration with a fair degree of correspondence with Walkley and Black’s method.