Microbial Metabolism of Paddy Soils (Part 2) : Composition of Gases and Organic Acids Contained in Soil of Paddy Field

Abstract

Determination of gases and organic acids in the soil of paddy field under water-logged condition were made at three periods during the growth of rice plant, for the purpose of exploring microbial metablism in paddy soil. Two soils applied were a badly drained meadow soil and a well drained brown lowland soil (see Table 1). The results obtained may be summarized as follows : 1. The meadow soil contained at every period a larger amount of total gases (except CO_2) than the brown lowland soil. The gas composition of the former was richer in N_2 and CH_4,and defficient in O_2 The composition of latter was similar to that of the former in July and September; but immediately after summer, airing in August caused the presence of O_2 and decreased CH_4. In both fields, H_2 gas content vigorously fluctuated; and this fluctuation seemed to the signifcance of H_2 as a metabolite. 2. When the content of total gases was larger, in the former, percentage of N_2 became to a higher level, but in the latter, that of CH_4 to a higher level. The presence of a larger quantity of N_2 in the former was supposed to be due to the denitrification in the reduced layer of paddy field. 3. The difference in the composition of organic acids between two soils could not be observed; and the acids cosisted mainly of acetic and formic acid. The concentration of organic acids was not different between them in July. However, in September this concentration was higher in the meadow soil than in the brown lowland soil.