Contrasting Soil Properties of Allophanic and Non-allophanic Horizons of Volcanic Ash Soilin Tohoku District, Japan
Nobuhiko Matsuyama, Haruki Fujisawa, Chihiro Kato, Choichi Sasaki, Masahiko Saigusa

This study examined the contrasting physical and chemical properties of allophanic and non-allophanic horizons in Japanese volcanic ash soils described in the Soil Survey Data Book before Land Reclamation. A total of 1133 investigation points and 4462 soil horizons from Tohoku District were divided into two groups based on their exchange acidity y1:allophanic horizonsy1< 6 and non-allophanic horizonsy1> 6. Volcanic ash soils from Tohoku District were characterized as dark, weakly adherent, soft, dry, humic, and active-Al rich. The soil acidities of the two horizons had significantly different pH, exchange acidity y1, and exchangeable Ca. Mean exchangeable Ca of LayerⅠ(topsoil),Ⅱ(subsoil), and Ⅲ(deeper subsoil) were 135±95, 98±83, and 78±80gkg-1, respectively, for allophanic horizons and 63±60, 52±49, and 59±59gkg-1, respectively, for non-allophanic horizons. The content of exchangeable Ca in the allophanic horizons was relatively high compared tonon-allophanic horizons (the ratio of non-allophanic/allophanic horizon exchangeable Ca was 0.47 and 0.53 in LayersⅠandⅡ). The differences in exchangeable Ca are ascribed to differences in recent tephra deposition with non-allophanic horizons receiving approximately half that deposited in allophanic horizons.

Full Text: PDF     DOI: 10.15640/jaes.v6n2a4