Abstract
We examined methods of soil improvement by accelerating the clay slate weathering in new reclaimed upland field at Hujisawa-cho Higashi-Iwai-gun Iwate-Prefecture. It showed that:
1.The subsoil improvement method, or soil treatment by the ripper dozer accelerated clay slate weathering. It is considered that this effect was retained more than for 4 years at the lower layer (15—30cm). However at the upper layer (0—15cm) it was lost about 4 years after reclamation.
2 . Soil treatment by the ripper dozer in winter, when the rock and soil was frozen, accelerated the clay slate weathering. In particular, big rocks, over 30mm in diameter, were broken. The effect was greater in the lower layer than the upper layer.
3 . The cultivation of pasture, wheat and fruit trees delayed clay slate weathering.
