Abstract
The objective of this research is to check the possibility of utilizing unused biomass to farm land for improving soil quality. This research was performed to investigate the changes of soil physical properties such as three-phase composition and soil hardness by incorporation of organic material, namely, saw dust and rice straw into volcanic ash soil, Andisol. We did compaction test, after that, we experimented three phase composition and soil hardness. In case of three-phase composition, gas phase in sample increased as mixing ratio of saw dust and rice straw increased. Mixing effect of rice straw to three-phase composition was more significant than that of saw dust on the basis of the same unit volume of mixing materials. Soil hardness decreased with increasing mixing ratio. We discussed the reason of the incorporation characteristics by the relationship between soil hardness, mixing ratio and dry bulk density, and concluded it was caused by increase of pores. In addition, it proved that soil hardness was also influenced by water content of soil.
