1992 Fiscal Year Final Research Report Summary
Accumulation of phosphorus in cultivated soils phosphate phase, sorption and desorption properties
| Project/Area Number |
02453119
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
土壌・肥料
|
|---|
| Research Institution | TOHOKU UNIVERSITY |
|---|
Principal Investigator |
NANZYO Masami Tohoku Univ. Fac. Agrie. Assistant professor, 農学部, 助教授 (60218071)
|
|---|
| Project Period (FY) |
1990 – 1992
|
| Keywords | cultivated soil / phosphorus / phosphorus accumulation / active aluminum / allophane / Andisol / exchangeable cation / reducing agent |
|---|
| Research Abstract |
This report consists of the following three points. 1. Mechanism of phosphate sorption and desorption of Andisols Clay fractions of six allophanic and nonallophanic andisols from northeastern Japan were used to determine the reactions associated with phosphate sorption. When phosphate was sorbed on these materials, aluminum dissolved in the solution at low pH precipitated, the amount positive charge decreased, pH rose, silicate and organic matter was released and the amount negative charge was increased. Contribution of the individual reactions depends on the type soils, pH and the amount of phosphate sorbed.
When phosphate was desorbed from these materials, the amount of negative charge was decreased. 2. Mechanism of phosphate sorption on smectic soils
Cultivated smectic soils contain large amount of exchangeable Ca and Mg though the contents of active aluminum and iron are much less than those for Andisols. These exchangeable cations react with phosphate to form CaHPO_4.2H_2O and MgNH_4PO_4._2O at around pH 7.3. Release of phosphate from phosphated hydrous iron oxide using organic reducing agents
Reducing agents having chelating effect such as chatecol and ascorbic acid showed higher effect for phosphate release from phosphated hydrous iron oxide than those without chelating effect.
|
