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Effect of redox conditions on phosphate exchangeability and iron forms in a soil amended with ferrous iron.
- Source :
- European Journal of Soil Science; Jun2009, Vol. 60 Issue 3, p386-397, 12p, 4 Charts, 4 Graphs
- Publication Year :
- 2009
-
Abstract
- Application of iron (Fe) -rich amendments to soils has been proposed as a means of decreasing phosphorus (P) losses from soils. However, anoxic conditions following soil saturation are known to increase Fe and P solubility in soils, thus cancelling out the potential benefits. Our aim was to evaluate the effects of continuous oxic, continuous anoxic and alternating anoxic/oxic conditions on P exchangeability and Fe forms in soil amended with Ca(OH)<subscript>2</subscript> and FeSO<subscript>4</subscript>. We incubated amended and unamended soils under these conditions for 8 weeks and measured Fe forms and P exchangeability. Under oxic conditions, addition of Ca(OH)<subscript>2</subscript> and FeSO<subscript>4</subscript> resulted in a strong decrease in P exchangeability and an increase in oxalate-extractable Fe. Mössbauer analyses suggested that an unidentified Fe oxide (D1oxide) with a strong sorbing capacity for P was precipitated. Under continuously anoxic conditions, P exchangeability and oxalate-extractable Fe increased with or without the amendments. Mössbauer analyses suggested that there was a partial dissolution of the D1oxide phase, precipitation of another unidentified Fe oxide (S3) and a reduction of structural Fe<superscript>3+</superscript> in phyllosilicate, thereby increasing soil negative charge. These transformations resulted in a strong increase in rapidly exchangeable P. Alternating anoxic and oxic periods induced the dissolution and precipitation of iron oxides and the increase and decrease in P exchangeability. Implications of the results for limiting P losses from grassland soils are discussed. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 13510754
- Volume :
- 60
- Issue :
- 3
- Database :
- Complementary Index
- Journal :
- European Journal of Soil Science
- Publication Type :
- Academic Journal
- Accession number :
- 39663436
- Full Text :
- https://doi.org/10.1111/j.1365-2389.2009.01135.x