Visualization and quantification of carbon “rusty sink” by rice root iron plaque: Mechanisms, functions, and global implications

作者：Liang Wei, Zhenke Zhu, Bahar S. Razavi, Mouliang Xiao, Maxim Dorodnikov, Lichao Fan, Hongzhao Yuan, Andrey A. Yurtaev, Yu Luo, Weiguo Cheng, Yakov V. Kuzyakov, Jinshui Wu, Tida Ge · 发表于：Global Change Biology · 年份：2022 · DOI：10.1111/gcb.16372 · 被引用次数：88 · 研究领域：Plant nutrient uptake and metabolism、Soil Carbon and Nitrogen Dynamics、Plant Micronutrient Interactions and Effects

Abstract Paddies contain 78% higher organic carbon (C) stocks than adjacent upland soils, and iron (Fe) plaque formation on rice roots is one of the mechanisms that traps C. The process sequence, extent and global relevance of this C stabilization mechanism under oxic/anoxic conditions remains unclear. We quantified and localized the contribution of Fe plaque to organic matter stabilization in a microoxic area (rice rhizosphere) and evaluated roles of this C trap for global C sequestration in paddy soils. Visualization and localization of pH by imaging with planar optodes, enzyme activities by zymography, and root exudation by 14C imaging, as well as upscale modeling enabled linkage of three groups of rhizosphere processes that are responsible for C stabilization from the micro‐ (root) to the macro‐ (ecosystem) levels. The 14C activity in soil (reflecting stabilization of rhizodeposits) with Fe2+ addition was 1.4–1.5 times higher than that in the control and phosphate addition soils. Perfect co‐localization of the hotspots of β‐glucosidase activity (by zymography) with root exudation (14C) showed that labile C and high enzyme activities were localized within Fe plaques. Fe2+ addition to soil and its microbial oxidation to Fe3+ by radial oxygen release from rice roots increased Fe plaque (Fe3+) formation by 1.7–2.5 times. The C amounts trapped by Fe plaque increased by 1.1 times after Fe2+ addition. Therefore, Fe plaque formed from amorphous and complex Fe (oxyhydr)oxides on t...