Abstract
The physical and mechanical properties of organic soils generated from volcanicash, and non-volcanic ash are examined from the viewpoint of farm land.
Samples were gathered from Kant-6 and KydshU districts and their physical and mechanical properties were measucred.
Moisture changes in the soil layer of tea garden were observed in Shizuoka Prefecture.
Mainresults obtained are as follows:
1. Ability of aeration increases with increase of the content of organic matters.
Coarse pores (index of aeration ability) increase up to 10% of the content of organic matters and over 10% it shows a stable coarse pore volume (about 20%).
2. Water holding capacity is closely related to the volume of fine pore. The volume of fine pore increases with increase of the content of organic matters.
Therefore, the moisture changes in the soil layer of tea garden (Kuroboku soil rich in organic matters) is mild in dry summer season.
On the other hand, the moisture in the non-volcanic ash soil is consumed rapidly, but drainage is delayed after heavy rainfall.
3. Soil cultivation is improved with increase of the content of organic matters.
4. Trafficability of kuroboku soil in the earth work is good, but volume change is very large compared with inorganic soils.
Strengh and peameability are not enough for the purpose of construction.
