Organic matter and rice yield

Decomposition patterns of 14C-labelled rice straw were studied, both in the field and in the laboratory. While anaerobic decomposition of straw in laboratory experiment was highly retarded, decomposition rates in submerged field were as high as under aerobic conditions. It is suggested that enhanced decomposition in submerged fields is caused by a very high activity and diversity of soil edaphon. Especially, nitrogen availability seems to be mainly dependent on soil biomass production and its turnover. Following the decomposition pattern in the field. A decay-accumulation series was used to relate soil carbon contents and seasonal carbon amendments. Based on long term yield experiments, a relationship between soil nitrogen, N-fertilizer and rice yields was established. (Author). 22 refs., 10 figs., 2 tabs