Determination of organic carbon in soils and fertilizers

Abstract

Many methods have been proposed to determine the total amount of organic carbon in soil; some of them determine only a percentage of the actual carbon content and therefore the results need the application of a correction factor. Methods for the determination of organic carbon in soil have been rarely extended to organic fertilizers and amendments. We propose a rapid method based on a modification of the original Springer and Klee10 procedure. Samples are oxidized for exactly 10 minutes with a mixture of 20 ml 2N K2Cr2O7 and 26 ml conc. H2SO4 at 160.+-.2.degree. C; the excess dichromate is titrated either potentiometrically or manually with FeSO4. The method is fast, accurate, and more reliable than other commonly used procedures. The procedure can be easily adopted for serial determination of carbon in both soils and organic fertilizers or amendments.