Microbial iron reduction compensates for phosphorus limitation in paddy soils

Chaoqun Wang; Lukas Thielemann; Michaela A Dippold; Georg Guggenberger; Yakov Kuzyakov; Callum C Banfield; Tida Ge; Stephanie Guenther; Patrick Bork; Marcus A Horn; Maxim Dorodnikov

doi:10.1016/j.scitotenv.2022.155810

Microbial iron reduction compensates for phosphorus limitation in paddy soils

Sci Total Environ. 2022 Sep 1:837:155810. doi: 10.1016/j.scitotenv.2022.155810. Epub 2022 May 11.

Authors

Affiliations

¹ Biogeochemistry of Agroecosystems, University of Goettingen, 37077 Goettingen, Germany. Electronic address: chaoqun.wang@forst.uni-goettingen.de.
² Biogeochemistry of Agroecosystems, University of Goettingen, 37077 Goettingen, Germany.
³ Biogeochemistry of Agroecosystems, University of Goettingen, 37077 Goettingen, Germany; Geo-Biosphere Interactions, University of Tuebingen, 72076 Tuebingen, Germany.
⁴ Institute of Soil Science, Leibniz University Hannover, 30419 Hannover, Germany.
⁵ Department of Soil Science of Temperate Ecosystems, University of Goettingen, 37077 Goettingen, Germany; Agricultural Soil Science, University of Goettingen, 37077 Goettingen, Germany; Peoples Friendship University of Russia (RUDN University), 117198 Moscow, Russia.
⁶ State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Institute of Plant Virology, Ningbo University, 315211 Ningbo, Zhejiang, China.
⁷ Institute of Microbiology, Leibniz University Hannover, 30419 Hannover, Germany.
⁸ Biogeochemistry of Agroecosystems, University of Goettingen, 37077 Goettingen, Germany; Department of Soil Science of Temperate Ecosystems, University of Goettingen, 37077 Goettingen, Germany.

PMID: 35561910
DOI: 10.1016/j.scitotenv.2022.155810

Abstract

Limitation of rice growth by low phosphorus (P) availability is a widespread problem in tropical and subtropical soils because of the high content of iron (Fe) (oxyhydr)oxides. Ferric iron-bound P (Fe(III)-P) can serve as a P source in paddies after Fe(III) reduction to Fe(II) and corresponding H₂PO₄^- release. However, the relevance of reductive dissolution of Fe(III)-P for plant and microbial P uptake is still an open question. To quantify this, ³²P-labeled ferrihydrite (30.8 mg P kg^-1) was added to paddy soil mesocosms with rice to trace the P uptake by microorganisms and plants after Fe(III) reduction. Nearly 2% of ³²P was recovered in rice plants, contributing 12% of the total P content in rice shoots and roots after 33 days. In contrast, ³²P recovery in microbial biomass decreased from 0.5% to 0.08% of ³²P between 10 and 33 days after rice transplantation. Microbial biomass carbon (MBC) and dissolved organic C content decreased from day 10 to 33 by 8-54% and 68-77%, respectively, suggesting that the microbial-mediated Fe(III) reduction was C-limited. The much faster decrease of MBC in rooted (by 54%) vs. bulk soil (8-36%) reflects very fast microbial turnover in the rice rhizosphere (high C and oxygen inputs) resulting in the mineralization of the microbial necromass. In conclusion, Fe(III)-P can serve as small but a relevant P source for rice production and could partly compensate plant P demand. Therefore, the P fertilization strategies should consider the P mobilization from Fe (oxyhydr)oxides in flooded paddy soils during rice growth. An increase in C availability for microorganisms in the rhizosphere intensifies P mobilization, which is especially critical at early stages of rice growth.

Keywords: Ferric iron reduction; Land use in subtropics; Phosphorus isotopes; Phosphorus pools and availability; Plant-microbial competition; Redox potential.

MeSH terms

Ferric Compounds / metabolism
Iron / analysis
Oryza*
Oxides
Phosphorus / metabolism
Soil
Soil Pollutants* / analysis

Substances

Ferric Compounds
Oxides
Soil
Soil Pollutants
Phosphorus
Iron