Physical and chemical properties and improvement of soil productivity in heavy clayey paddy fields 4. effect of acceleration of surface soil drying on initial growth of rice plants in heavy clayey paddy fields
Maeda, K.; Minami, M.
Bulletin of Hokkaido Prefectural Agricultural Experiment Stations 44: 1-11
The effects of soil environmental factors under flooded and non-flooded conditions on initial growth of the rice plants were investigated. Two soils were studied gley lowland soil of poorly drained paddy fields (A) and brown lowland soil of well-drained paddy fields (B). The rate of increase in dry matter produced of rice plants from tillering to young panicle formation and the amount of dry matter produced at the latter stage were smaller in A than B; in particular in A, whose paddy fields were extremely soft in 10p975 and 1976, the amount of growth in the initial stage was markedly smaller in plots to which rice straw was applied. In A to which rice straw was applied the degree of advancement in reduction of soil was markedly mitigated and the growth in the initial stage of rice plants became favorable as the soil dried. This trend was more conspicuous in plots treated with rice-hull underdrainage than in the control with earthen-pipe underdrainage. In the heavy ill-drained paddy fields, if the drying degree of surface soil is sufficient at plowing time, it is easy to maintain the environment of the surface soil in a favorable level for oxidization after flooding, which is helpful for rice plants to root firmly and grow well in the initial atage.