圃場整備後の水田土層の特性について

In case of readjustment and regrouping of paddy fields after land consolidation project, different characters of the original fields should have some influence on the characteristics of the expanded field, especially on the variation of soil condition. Then, two of 50a (100×50m) paddy fields, each of which was consolidated from five of 10a (20×50m) fields,were investigated about the distribution of water content and cone index of the field. The water content of surface soil layer was measured after drainage of residual water at 15 (3 x 5) intersecting points of cross lines at equal intervals. And data of cone index were measured at the same places as in the case of water content, and averaged every 10cm depth (0～10cm, 10～20cm, 20～30cm, respectively). The results of these investigations are as follows. i) In the surface soil layer (0～10cm), where homogeneity of soil condition has been progressed, the measured data are affected rather by the characteristics of the expanded field such as variation of mulching and surface elevation, than by the characteristics of the original field. ii) In the subsurface soil layer of 10～20cm and 20～30cm depth, owing to differences of characters of each original paddy field, there are no homogeneity of cone index. These show the necessity of considering homogeneity of field conditions, especially of the soil, for the purpose of apposite estimation of trafficability of farm machinery and efficient usage of it on the expanded paddy field, on the land consolidation work.