EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Can ferric iron reduction in paddy soils compensate phosphorus limitation of rice plants and microorganisms?

Chaoqun Wang1, Michaela Dippold1,2, Georg Guggenberger3, and Maxim Dorodnikov1,4
Chaoqun Wang et al.
  • 1Biogeochemistry of Agroecosystems, University of Göttingen, 37077 Goettingen, Germany (;;
  • 2Geo-Biosphere Interactions, University of Tuebingen, 72076 Tuebingen, Germany (
  • 3Institute of Soil Science, Leibniz University Hannover, 30419 Hannover, Germany (
  • 4Department of Soil Science of Temperate Ecosystems, University of Goettingen, Goettingen 37077 Germany (

Biogeochemical cycles of phosphorus (P) and iron (Fe) are tightly intertwined, especially in highly weathered and acidic subtropical and tropical soils rich in ferric Fe (Fe(III))oxides. In low-redox and P-deficient paddy soils, the quantitative contribution of the reductive dissolution of Fe(III)-bound P (Fe-P) to the demands of rice plants (Oryza sativa L.) and microorganisms remains unclear. We hypothesized that Fe(III) reductive dissolution can cover the P demand of microorganisms but not of rice plants during the initial growth stages, when P demand is high but the root system is still limited. We grew pre-germinated rice plants for 33 days in flooded rhizoboxes filled with a paddy soil of poor P availability. 32P-labeled orthophosphate sorbed to ferrihydrite (80 kg ha-1) was supplied either (1) in polyamide mesh bags (30 μm mesh size) to prevent roots from directly mobilizing Fe-P (Pellets-mesh bag treatment), or (2) in the form of pellets directly to the soil without mesh bags to enable roots’ accessing the Fe-P (Pellets-no-mesh bag treatment). With the application of Fe-P directly to the soil, P was more available resulting in the increases in microbial biomass carbon (MBC) by 18–55% and nitrogen (MBN) by 4–108% in rooted soil as compared to the pellet not available to roots directly. The maximum enzyme activities (Vmax) of phosphomonoesterase and β-glucosidase followed this pattern. During rice root growth, MBC and microbial biomass phosphorus (MBP) in both rooted and bottom bulk soil gradually decreased by 28–56% and 47–49%, respectively. In contrast to our hypothesis, the contribution of Fe-P to MBP strongly decreased from 4.5% to almost zero during 10–33 days after rice transplantation, while Fe-P compensated up to 16% of the plant P uptake 33 days after rice transplantation, thus outcompeting microorganisms.

How to cite: Wang, C., Dippold, M., Guggenberger, G., and Dorodnikov, M.: Can ferric iron reduction in paddy soils compensate phosphorus limitation of rice plants and microorganisms?, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7241,, 2022.

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