Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

Organic Matter Accelerated Microbial Iron Reduction and Available Phosphorus Release in Reflooded Paddy Soils

Version 1 : Received: 8 December 2023 / Approved: 8 December 2023 / Online: 11 December 2023 (09:10:43 CET)

How to cite: Liu, X.; Shu, Y.; Li, K.; Wang, H.; Bi, Q.; Wang, H.; Sun, C.; Lin, X. Organic Matter Accelerated Microbial Iron Reduction and Available Phosphorus Release in Reflooded Paddy Soils. Preprints 2023, 2023120664. https://doi.org/10.20944/preprints202312.0664.v1 Liu, X.; Shu, Y.; Li, K.; Wang, H.; Bi, Q.; Wang, H.; Sun, C.; Lin, X. Organic Matter Accelerated Microbial Iron Reduction and Available Phosphorus Release in Reflooded Paddy Soils. Preprints 2023, 2023120664. https://doi.org/10.20944/preprints202312.0664.v1

Abstract

The cycling of soil phosphorus (P) is inherently linked with soil organic carbon-iron (C-Fe) cycling, yet empirical integration of these processes within paddy soils remains scarce. In this study, we conducted a microcosm experiment using paddy soils subjected to six distinct fertilization regimes involving varying P inputs for five years. In addition to evaluating P activation under reflooding conditions, we assessed the Fe reduction process and characterized the properties of dissolved organic matter (DOM) at the molecular level using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), alongside profiling the composition of soil microbial communities with high-throughput sequencing. Our findings revealed that after 25 days of reflooding, soil Olsen-P content increased by an average of 73% compared to its initial state, showing a strong correlation with the Fe reduction process. Specifically, treatments involving pig manure application exhibited higher Fe reduction rates and enhanced P activation, highlighting the role of organic matter in facilitating Fe reduction. Investigations on the relative abundance of typical iron-reducing microbes further supported their importance in P activation, but the rate of iron reduction is limited by soil organic matter content. Delving deeper into DOM properties, soil DOM composition profiling and network analysis suggested that high-molecular-weight DOM, particularly lignins, served as the primary resources driving Fe reduction by iron-reducing microbes, consequently promoting Fe reduction and P release. Taken together, our study assembled the C-Fe-P cycling dynamics in paddy soils, emphasizing the pivotal role of microbial-driven Fe reduction facilitated by soil DOM in P availability and subsequently sustainable agricultural practices.

Keywords

 manure application; P availability; soil biogeochemistry; microbial carbon mineralization; ironcarbon cycles

Subject

Environmental and Earth Sciences, Soil Science

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