Abstract
1) We investigated the possibility to utilize troprical leguminous green manure crops for improvement of soil physical properties and management of soil fertility in ill-drained clayey paddy fields in Hokuriku district.
2) We carried out this experiment in 1988 at the field of Hokuriku National Agricultural Experiment Station. The crops used were Sesbania cannabia, S. rostrata and Crotalaria juncea. We mesured productivity of dry matter, development of root-systems, and degree of drying and oxidization of soil to estimate the utility value.
3) The dry matter yields of S. cannabia, S. rostrata and C. juncea were 1.4, 1.2 and 0.9kg/m2 respectively. The cracks were formed and the drying and the oxidization were activated in the lower layer of the soil by the development of the root systems. The position grey soil appeared in the soil was lowered till 33-45cm, and the depth of root of S. cannabia, s. rostrata and C. juncea were 80, 62 and 52cm respectively.
4) The leguminous bacteria of S. cannabia, S. rostrata and C. juncea was Rhizobium. Azorhizobium and Bradyrhizobium respectively. Azorhizobium which forms the nodules not only on root, but on stem of S. rostrata, was identified in fields for the first time in Japan.
