Soil Amendment Using Leguminous Green Manure in Post-Decontamination Field in Hamadori, Fukushima Prefecture

Abstract

Soil amendment using leguminous green manure in post-decontamination field in Hamadori, Fukushima Prefecture (Tomioka Town, Fukushima Prefecture) is introduced in this paper. Especially hairy vetch, which has a high soil improvement effect, was explained in detail about the cultivation method and utilization characteristics of green manure. Post-decontamination field is often covered with mountain soil (mountain sand) with low nitrogen fertility, and the soil becomes hard, resulting in poor drainage. In order to plant leguminous green manure in such fields, it is necessary to improve the drainage by constructing open drains. In addition, leguminous plants must have compatible rhizobia living in the soil, and inoculation of superior rhizobia is effective in promoting growth. The planting of hairy vetch improves soil physical properties, increases the air phase ratio of the soil, and improves drainage of the field. Since the amount of nitrogen accumulated in the shoot of hairy vetch is more than 25 g-N m^-2, a large amount of nitrogen can be supplied by incorpolating into the soil. The decomposition of hairy vetch residue in soil is rapid compared with non-legume green manure and 90 % of the residue is decomposed for about one month in summer, but about half of the nitrogen derived from hairy vetch remains in the soil and becomes soil nitrogen. When paddy rice was cultivated after planting hairy vetch in post-decontamination field, the rice growth and yield was promoted in the hairy vetch planting treatment compared to the non-planting treatment. From the above, introduction of leguminous green manure such as hairy vetch to post-decontamination field is effective in soil amendment such as soil physical properties and nitrogen fertility.