ABSTRACT
In a long-term experiment, the influence of straw manuring in spring and autumn on the biological activity of a lessive chernozem soil was examined. The quantity of carbon dioxide, evolved by the plots during May and June, showed an increase in soil respiration by straw manuring. Increasing amounts of nitrogen, given together with straw, had no significant influence on the quantity of carbon dioxide evolved. The base respiration, however, showed increasing rates proportional to increasing amounts of nitrogen. The variants manured with straw in autumn were superior to those manured in spring. For covering the efficiency of soil respiration, the field method applied noes not seem suitable. With high N-supply (200 kg/ka), the relative respiration rates show good stability of the organic substance, present in soil. This stability is higher with straw manuring in spring than in autumn. Straw supply in autumn influences the yield more favourably. Direct relation between the quantity of carbon dioxide evolved and yield cannot be inferred.
