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J. Jpn. Soc. Soil Phys.
 No. 21, p. +3,0 ,**+

ῌ *ῌῌ *ῌ **ῌ***Features of Soil Physical Proﬁles Generated by Accumulation Processes andAnthropogenic E#ects
Soil Physical Properties of Bibai Peat Land (ῌ)Hiromi IMOTO*, Tsuyoshi MIYAZAKI*, Taku NISHIMURA** and Masashi NAKANO**** Graduate School of Agricultural and Life sciences, The University of Tokyo** Graduate School of Agricultural Science,Tokyo University of Agriculture and Technology*** Faculty of Agriculture, Kobe University
Abstract
Anthropogenic e#ects on peat soils were investigated by comparing the physical properties ofsoils taken from undisturbed natural moss ﬁeld, adjacent rice ﬁelds, adjacent upland ﬁelds andadjacent windbreak areas in Bibai, Hokkaido Japan. Following the soil proﬁle observations, insitu water contents, bulk densities, particle densities, ignition losses, and shrinkage index wereexamined in the laboratory.
In lowmoor peat areas, the upland ﬁelds were relatively dry and the shrinkage indexes wererelatively 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 e#orts of soil dressing continued up
to now.

In the highmoor peat area, in situ water contents were as high as +,*** to +,/**῍ but theignition losses were not necessary higher than transitional moor. Against our expectation, theshrinkage degrees versus water contents of highmoor were lower than those of lowmoor.
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