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Iron reduction and changes in cation exchange capacity in intermittently waterlogged soil

Version 2 2024-06-04, 08:40
Version 1 2016-10-12, 12:32
journal contribution
posted on 2024-06-04, 08:40 authored by F Favre, D Tessier, M Abdelmoula, JM Génin, Will GatesWill Gates, P Boivin
The long-term effects of intermittent flooding on soil properties were studied in field experiments on a Vertisol cropped with rice in Senegal. The dominant clay minerals were smectite and kaolinite. When the soil was reduced after flooding, its cation exchange capacity (CEC) increased to twice that of its oxidized, unflooded state. Mössbauer spectroscopy showed an increase in smectite structural Fe II upon reduction, which explained a part of the increase in CEC. The rest of the increase was attributed to the removal of iron oxyhydroxide coatings by reductive dissolution. The reduction and dissolution of oxides under the field conditions were substantiated by analysis of the surfaces of vermiculites buried in the Ap horizons of the cropped and the non-cropped soils. The redox-induced CEC changes were found to be reversible after 22 cycles of rice cropping. Nevertheless, the structural Fe and free Fe contents of the rice field Ap horizon were less than those of soil in uncropped neighbouring land, suggesting that inundation induced weathering and eluviation of the minerals. The observed changes in CEC and related redox reactions may substantially modify proton, anion and cation balances in intermittently flooded soils.

History

Journal

European journal of soil science

Volume

53

Pagination

175-183

Location

Chichester, Eng.

ISSN

1351-0754

Language

eng

Publication classification

C1.1 Refereed article in a scholarly journal

Copyright notice

2002, Blackwell Science Ltd.

Issue

2

Publisher

Wiley

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