Pedosphere 27(1): 96--105, 2017
ISSN 1002-0160/CN 32-1315/P
©2017 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Influence of soil properties on zinc solubility dynamics under different redox conditions in non-calcareous soils
M. A. B. BUNQUIN1, S. TANDY2, S. J. BEEBOUT1 and R. SCHULIN2
1Crop and Environmental Sciences Division, International Rice Research Institute, College, Los Baños Laguna 4031 (Philippines)
2Soil Protection, Institute ofTerrestrial Ecosystems, ETH Zurich, Zürich CH-8092 (Switzerland)
ABSTRACT
      Zinc (Zn) deficiency in paddysoils is often a problem for rice production. Flooding can decrease metalavailability in some non-calcareous soils through different mechanisms associated with soil redox status. Laboratory experiments were performed in order to better understand the processes that governed the dynamics of Zn in non-calcareous paddy soils at varying redox potentials (Eh). Air-dried non-calcareous soil samples collected from four different paddy field sites in the Philippines were submerged and incubated in a reaction cell with continuous stirring and nitrogen purging for 4 weeks, and then purged with compressed air for another week to reoxidize the system. The Eh of the four soils started at 120 to 300 mV, decreased to --220 to --300 mV after 100 to 250 h of reduction, and was maintained at this low plateau for about 2weeks before increasing again upon reoxidation. Zinc solubility showed contrasting patterns in the four soils, with two of the soils showing a decrease in soluble Zn as the Eh became low, probably due to zinc sulfide (ZnS) precipitation. In contrast, the other two soils showed that Zn solubility was maintained during the reduced phase which could be due to the competition with iron (Fe) for precipitation with sulfide. Differences in the relative amounts of S, Fe, and manganese (Mn) oxides in the four soils apparently influenced the pattern of Zn solubility after flooding.
Key Words:  microcosm, paddy soil, precipitation, rice, soil sulfide, speciation, Zn availability
Citation: Bunquin, A. B., Tandy, S., Beebout, S. J. and Schulin, R. 2017. Influence of soil properties on zinc solubility dynamics under different redox conditions in non-calcareous soils. Pedosphere. 27(1): 96-105.
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