Determination of the decomposable part of soil organic matter in arable soils∗

Abstract

As part of an EU project different fertilization treatments of 7 long‐term fertilization experiments at 6 sites were investigated with regard to their soil organic matter (SOM) content and its mineralizable part. Organic and mineral fertilization increased the content of organic C in all investigated experiments, with an higher increase in manured plots than in NPK plots. This increase of soil organic C occured mainly in its decomposable part. Results of five different procedures for estimation of the decomposable part of soil organic matter will be presented: 1. Determination of hot water soluble carbon (Chws) 2. Basal respiration from 4th to 7th day of incubation 3. Long‐term respiration during 35 days of incubation 4. Calculated values of the decomposable carbon based on 35 days respiration 5. Nitrogen mineralization during 35 days of incubation. The comparison of the results obtained by individual methods by means of correlation coefficients has shown the best fit for the hot water soluble C and the basal respiration.