Water Quality: Improving Water Quality Utilizing Hemp

Abstract

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.