Abstract
This report deals with the effects of the some soil properties that influences on the volume weight of forest soils. Air dried materials were used for these tests.
1) The soils were filled in the messcylinder (20 cc), and droped them down from 5cm high, then, the volume weight increased exponentialy according to the frequency of the impacts.
As far as the same soil was used, the volume weight on the 20 th impacts were approximately censtant, unrelated with the initial volume weight. And so the volume weight on the 20 th impacts is called the volume weight in the compact condition in this report.
2) The soil texture, specific gravity and so on were influenced to the volume weight (compact), but it seemed that these influences were not so great compared with that of the content of aggregate structure.
3) The volume weight (compact) were voried greatly with the content of aggregate. According to the increase of grain size, the volume weight (compact) gradually increased as far as the single grain structure is concerned, but these gradually decreased on the case of the aggregate. Therefore, it seemed that the volume weight (compact) were closedly related to the content of aggregate, especially to that of the large grains.
4) On the soils that have no great differences on the soil texture and specific graeity, the volume weight (compact) represent approximately the content of aggregate. In addition to this factor, the compactness closedly related to the volume weight in the natural condition.
Therefore, the volume weight (natueal) are mainly influenced by two soil properties, that are the content of aggregate and the compactness.
