Abstract
Anthropogenic effects on peat soils were investigated by comparing the physical properties of soils taken from undisturbed natural moss field, adjacent rice fields, adjacent upland fields and adjacent windbreak areas in Bibai, Hokkaido Japan. Following the soil profile observations, in situ water contents, bulk densities, particle densities, ignition losses, and shrinkage index were examined in the laboratory. In lowmoor peat areas, the upland fields were relatively dry and the shrinkage indexes were relatively high. Both in lowmoor and transitional moor peat areas, the bulk densities of surface soils in rice fields and upland fields were very high due to the efforts of soil dressing continued up to now. In the highmoor peat area, in situ water contents were as high as 1,000 to 1,500% but the ignition losses were not necessary higher than transitional moor. Against our expectation, the shrinkage degrees versus water contents of highmoor were lower than those of lowmoor.
