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Studies on the mechanisms of fixation and release of ammonium in paddy soils after flooding. I. Effect of iron oxides on ammonium fixation
Author(s) -
Scherer Heinrich W.,
Zhang Yongsong
Publication year - 1999
Publication title -
journal of plant nutrition and soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 87
eISSN - 1522-2624
pISSN - 1436-8730
DOI - 10.1002/(sici)1522-2624(199912)162:6<593::aid-jpln593>3.0.co;2-l
Subject(s) - vermiculite , chemistry , ammonium , soil water , clay minerals , goethite , ferrihydrite , nuclear chemistry , environmental chemistry , mineralogy , horticulture , geology , soil science , organic chemistry , adsorption , biology
Experiments were conducted with two typical paddy soils from China and a vermiculite to study the influence of iron oxides on the fixation and release of ammonium. Removing iron oxides, especially amorphous iron oxides, from the soils favoured the release of non‐exchangeable NH 4 ‐N and stimulated the fixation of NH 4 ‐N in the presence of added (NH 4 ) 2 SO 4 . Addition of artificial goethite and hematite to the original soils or to the soils free of iron oxides reduced the fixation of NH 4 + ‐ions. This effect was also observed with vermiculite. We conclude that the coating of clay minerals with iron oxides has an impact on the diffusion of NH 4 + ‐ions into and out of the interlayers of the clay minerals. The reduction and dissolution of iron oxides induced by low redox potential (E h ) after flooding of paddy soils is assumed to be an important mechanism controlling NH 4 + ‐fixation in paddy fields.