Vast and beautiful grassland landscapes in the Aso Kuju National Park have been maintained by human activities e.g. controlled burning, pasturage and mowing. However, the aging of local farmers and the stagnation of livestock industry make such grassland management increasingly difficult.

This paper shows that rice husk ash (RHA) changes the mechanical property of magnesium improved soil. Splitting test was conducted on two types of soil (normal and mixed with RHA). Fracture process was qualitatively evaluated by image analysis and acoustic emission (AE).

The purpose of this study is to clarify land improvement method of early collective housing sites developed by Japan housing corporation during 1960's-70's constructed on marshland on Nakagawa lowland in Saitama prefecture - Misato, Yoshikawa, Takesato, and Soka-Matsubara.