Soil Zn deficiency causes malnutrition of both rice plants and human rice consumers. Most rice soils are intermittently submerged with frequent redox potential fluctuations. As the major redox-active structural component, Fe-oxides and -hydroxides affect Zn solubility in these soils. Rice roots oxidize the rhizosphere, resulting in deposition of Fe-oxide plaque on the root surface, creating sites for Zn sorption, which decreases its solubility, but also localizing it near plant root membranes. Our objective was to understand how Fe-oxides control Zn solubility in the soil and rhizosphere of rice plants. We used anaerobic stirred slurries to explore soil solution chemistry in 4 soils with varying Fe-oxide content, measuring Fe, Mn, Zn, sulfide, sulfate, and dissolved organic carbon over time during redox cycles. Modeling the data with VisualMinteq confirmed that Zn interactions with changing surfaces of Fe-oxides are an important factor, along with the formation of metal sulfides, in limiting Zn solubility in soils with fluctuating redox conditions.

Zinc interactions with Fe-oxides during redox fluctuations in submerged rice soils

244th National Meeting (2012)

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