The Kanto Loam...a volcanic ash soil distributed in the Kanto Region...has many properties unfavourable for reclamation such as high percolation rate in paddy, fields, high susceptibility to wind erosion, and excessive stickiness in ploughing. It is necessary to clarif relations between water and soil to improve these properties.<BR>The main results of our studies are as follows:<BR>1. Porosity of the Kanto Loam is about 80% in the surface soil (A horizon) as well as in the subsoil (B-C horizon). It is to be noted that the subsoil has such a high porosity in spite of its low humus content of 2-3%.<BR>2. The Kanto Loam has granular structure in the surface soil and massive structure in the subsoil. The massive subsoil contains a number of considerably large channels in it and shows a permeability almost as high as that of the granular surface soil.<BR>When the subsoil gets exposed to repeated drying and wetting or root influence in the process of land reclamation, its massive structure seems to change gradually to granular structure through gradation of nutty structure.<BR>3. The subsoil has a large quantity of non-free water (connected to soil particles by a force greater than pF 4.2), which is remove, irreversibly by air-drying. This property seems to originate in the characteristics of allophane contained in the subsoil.<BR>4. The liquid limit, plastic limit and plasticity index of the subsoil diminish and its maximum dry density on compaction test increase through air-drying. These are natural results of the irreversible removal of the non-free water.<BR>5. The apparent volume of the subsoil clod decreases gradually as the drying goes on from pF 0 to 4.2, and the shrinkage in this moisture range is reversible as in the case of non-volcanic ash soils. But the shrinkage corresponding to the decrease of moisture from pF 4.2 to 7 is rapid and irreversible. These phenomena are also closely related to the behaviour of the non-free water.<BR>6. The specific surface area of the Kanto Loam is markedly large in comparison with that of non-volcanic ash soil and is nearly as large as that of bentonite.<BR>7. The paste of the subsoil shows “the negative shear rate thixotropy flow”.<BR>8. The subsoil shows no distinct peak of dry density on compaction test in drying process, while non-volcanic ash soil generally shows a marked peak.<BR>9. Having high porosity and granular structure, the A horizon acts as a temporary store of water, capacity of which are estimated to be 100 mm of water depth, when it is excessively irrigated or poured by rain.<BR>10. Having high porosity and massive structure penetrated by a number of large channels, the B-C horizon has a high permeability when saturated, and a high retention capacity when unsaturated.