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The effect of soil flooding on the transformation of Fe oxides and the adsorption/desorption behavior of phosphate
Author(s) -
Zhang Yongsong,
Lin Xianyong,
Werner Wilfried
Publication year - 2003
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/jpln.200390014
Subject(s) - chemistry , adsorption , soil water , desorption , sorption , environmental chemistry , oxalate , phosphate , inorganic chemistry , soil science , geology , biochemistry , organic chemistry
As repeatedly reported, soil flooding improves the availability of P to rice. This is in contrast with an increased P sorption in paddy soils. The effects of soil flooding on the transformation of Fe oxides and the adsorption/desorption of P of two paddy soils of Zhejiang Province in Southeast‐China were studied in anaerobic incubation experiments (submerging with water in N 2 atmosphere). Soil flooding significantly increased oxalate‐extractable Fe (Fe ox ), mainly at the expense of dithionite‐soluble Fe (Fe DCB ), as well as oxalate‐extractable P (P ox ), but decreased the ratio of P ox /Fe ox . Flooding largely increased both, P adsorption and the maximum P adsorption capacity. The majority of newly sorbed P in the soils was P ox , but also more newly retained P was found to be not extractable by oxalate. Flooding also changed the characteristics of P desorption in the soils. Due to a decrease of the saturation index of the P sorption capacity, P adsorbed by flooded soils was much less desorbable than that from non‐flooded soils. There are obviously significant differences in the nature of both, the Fe ox and P ox fractions under non‐flooded and flooded conditions. The degree of the changes in Fe ox , P ox , P adsorption and P desorption by flooding depended on the contents of amorphous and total Fe oxides in non‐flooded soils. Our results confirm that the adsorption and desorption behavior of P in paddy soils is largely controlled by the transformation of the Fe oxides. The reasons of the often‐reported improved P availability to rice induced by flooding, in spite of the unfavorable effect on P desorbability, are discussed.