Drying effect on mineralizations of microbial cells and their cell walls in soil and contribution of microbial cell walls as a source of decomposable soil organic matter due to drying

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Abstract
1) The mineralization of several kinds of microbial cells added to soil were accelerated considerably by the drying effect. 2) When microbial cells were roughly divided by mechanical procedure into two parts, i.e., cytoplasmic and cell wall substances, and separately added to soil with or without drying previously, the former was mineralized very quickly both with and without drying previously and its mineralization was not accelerated by the drying effect. The latter without drying previously was mineralized rather slowly, and the latter with drying previously was mineralized very quickly and remarkably. Furthermore, the former with and without drying previously left hardly any residual matter in soil, but the latter without drying previously left considerable residual matter because of making a complex resistant to microbial decomposition with colloid materials such as clay minerals and humus, and mineralization of the residual matter was remarkably accelerated by the drying effect. 3) From the results mentioned above, it may be concluded that microbial cell wall substances remaining in soil clearly contribute as a source of soil organic matter becoming decomposable due to drying.