Abstract
We adopted the 'inter-row strip tillage' (IST), in which furrows between rows are tilled and seed is sown on the ridge which is covered with the tilled furrow soil, to the soybean cultivation in upland field converted from paddy field (UFCP), and examined its effect on the soil water content, and the growth and yield of soybean. Three phase of no-tillage soil of the ridge in IST was different from harrowed soil in conventional tillage, and showed a higher ratio of solid and liquid phase. Furthermore, no-tillage soil in IST had a higher water content in a drought condition and lower water content in an excess moisture condition compared with harrowed soil in conventional tillage. On the other hand, plants in IST had longer plant length, larger number of node on the main stem, and larger dry weight at flowering stage. A similar tendency of growth at the flowering stage was observed continuously from pod-setting to grain filling stage. The yield in IST was superior to that in conventional tillage, due to a larger number of pod, and heavier 100-seed-weight, although the grain quality was not affected by the tillage method. These results suggest that the superior growth and higher yield in IST were attributed to the property of no-tillage soil in IST, which alleviated the fluctuation of soil water content in UFCP. The correlation of soil permeability and property with the effectiveness of IST, and also improvement of operation efficiency of IST are subjects for further study.
