Aluminum Dynamics in Nonallophanic Andosols from Northeastern Japan

We studied Al dynamics in nonallophanic Andosols from northeastern Japan by determination of Al solubility and Al release rates, selective dissolution analyses of active Al fractions, and examination of liming effect on the active Al. Aluminum solubility of the nonallophanic Andosols was lower than that of gibbsite in the lower pH range and showed oversaturation in the higher pH range, indicating that the Al solubility was controlled by Al-humus complexes. There was a close relationship between Al saturation (KCl-extractable Al/effective CEC) and the amount of pyrophosphate extractable Al, indicating that exchangeable Al is equilibrated with organically complexed Al. Liming (CaCO_3 treatment) largely reduced the amount of organically complexed Al (pyrophosphate- and CuCl_2-extractable Al), confirming that a portion of Al-humus complexes are labile

Changes in Elemental Composition with Andosolization

A total of 57 elements in volcanic ash soils from 18 pedons distributed in Japan were analyzed and the relationships between noncrystalline material content and that of individual elements were examined. The content of the noncrystalline materials was estimated by using acid-oxalate extraction. Oxalate-extractable Fe (Fe_o) and Al (Al_o) corresponds to Fe in ferrihydrite and Al in allophane-imogolite plus Al complexed with humus, respectively. Silicon and alkaline or alkaline-earth elements such as Na, K. Ca, and Sr tended to decrease during the process of volcanic ash soil formation, i.e., andosolization. In contrast, the contents of Al, Y and the first transition metals tended to increase with the increasing content of noncrystalline materials. The first transition metals showed a high correlation with Feo suggesting their similarity in chemical behavior during andosolization. The lanthanoid elements tended to increase with the increasing Al_o and Fe_o content

Recent Trends in the Nutrient Status of the Paddy Field Soil in Japan and Related Topics(Frontiers in Rice Science -from Gene to Field-,The 100^<th> Anniversary of Tohoku University, International Symposium)

Paddy rice production is important for Asian people because rice is their traditional staple diet and it is a reliable crop for them. Rice shows second highest yield per ha next to maize and sustainability of paddy rice production is excellent. High sustainability of paddy rice production is at least partly due to flooding and nutrient supply through irrigation water. Yield and quality of paddy rice are better than those of upland rice. In this paper, we review characteristics of the paddy field soils and recent trends in the nutrient status of Japanese paddy field soils, and then we introduce our recent research topics on N, P, S and Cd in the paddy field soil

Organic Carbon Accumulation in Andosols: (1) Unaccounted Andosols in Japanese Forest Soil

Symposium Pape

Use of Soil Database for Pedological Research as Exemplified by Volcanic Ash Soils

Original Pape

Factors Affecting Organic Carbon Accumulation in Humus Horizons of Andosols from the Tohoku University World Andosol Database

Poster Sessio

Recent trends in the nutrient status of the paddy field soil in Japan and related topics

Special Revie