Organo-organic interactions dominantly drive soil organic carbon accrual
Data files
Jan 15, 2024 version files 85.95 KB
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Data_Kang_et_al_2024.xlsx
82.42 KB
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README.md
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Abstract
Organo-mineral interactions have been regarded as the primary mechanism for the stabilization of soil organic carbon (SOC) over decadal to millennial timescales, and the capacity for soil carbon (C) storage has commonly been assessed based on soil mineralogical attributes, particularly mineral surface availability. However, it remains contentious whether soil C sequestration is exclusively governed by mineral vacancies, making it challenging to accurately predict SOC dynamics. Here, through a 400-day incubation experiment using 13C-labeled organic materials in two contrasting soils (i.e., Mollisol and Ultisol), we show that despite the unsaturation of mineral surfaces in both soils, the newly incorporated C predominantly adheres to "dirty" mineral surfaces coated with native organic matter (OM), demonstrating the crucial role of organo-organic interactions in exogenous C sequestration. Such interactions lead to multilayered C accumulation that is not constrained by mineral vacancies, a process distinct from direct organo-mineral contacts. The coverage of native OM by new C, representing the degree of organo-organic interactions, is noticeably larger in Ultisol (~14.2%) than in Mollisol (~5.8%), amounting to the net retention of exogenous C in Ultisol by 0.2–1.3 g kg−1 and in Mollisol by 0.1–1.0 g kg−1. Additionally, organo-organic interactions are primarily mediated by polysaccharide-rich microbial necromass. Further evidence indicates that iron oxides can selectively preserve polysaccharide compounds, thereby promoting the organo-organic interactions. Overall, our findings provide direct empirical evidence for an overlooked but critically important pathway of C accumulation, challenging the prevailing “C saturation” concept that emphasizes the overriding role of mineral vacancies. It is estimated that, through organo-organic interactions, global Mollisols and Ultisols might sequester ~0.1–1.0 Pg C and ~0.3–1.7 Pg C per year, respectively, corresponding to the neutralization of ca. 0.5%–3.0% of soil C emissions or 5%–30% of fossil fuel combustion globally.
README: Organo-organic interactions dominantly drive soil organic carbon accrual
https://doi.org/10.5061/dryad.m0cfxpp9w
This README file was generated on 2024-01-12 by Jie Kang.
This dataset supports the findings reported in Kang, J., Qu, C., Chen, W., Cai, P.,Chen, C., & Huang, Q. (2024). Organo–organic interactions dominantly drive soil organic carbon accrual. Global Change Biology, 30, e17147. https://doi.org/10.1111/gcb.17147.
Data descriptions by sheet:
Sheet1 - General description
MAOC - Mineral-associated organic carbon
- Unit: g kg-1.
- MAOC source -- MAOC fraction derived from exogenous carbon (new) or endogenous carbon (native). While the total MAOC is the sum of new MAOC and native-MAOC.
- Soil type -- Mollisol and Ultisol used in the study.
- Treatment -- Whether the soil sample is unamended (control) or amended with straw or glucose.
- Mean & SD -- Mean values and standard deviation (n = 3).
MNC - Microbial necromass carbon
- Unit: g kg-1.
- MNC source -- MNC fraction derived from fungal necromass or bacterial necromass. While the total MNC is the sum of fungal MNC and bacterial MNC.
SR-FTIR - Synchrotron radiation-based Fourier transform infrared microspectroscopy
- Values are summed peak intensities at the corresponding peak positions for each functional group.
- Multiple data points were collected within the measured area for each sample.
- Clay -- Phyllosilicates, clay–OH stretching at 3620 cm−1.
- Fe-O -- Fe oxides, Fe–O stretching at 690 cm−1.
- Al-O -- Al oxides, Al–O stretching at 915 cm−1.
- Phen -- Phenolics, OH stretching at 3379 cm−1.
- Alip -- Aliphatics, a combination of CH3 and CH2 stretching at 2920 and 2856 cm−1 and CH deformation at 1419 cm−1
- Carb -- Carboxylics, a combination of C=O stretching at 1716 cm−1 and C–O stretching and OH deformation at 1252 cm−1
- Arom -- Aromatics, C=C vibration at 1618 cm−1.
- Poly -- Polysaccharides, C–O stretching at 1036 cm−1.
NanoSIMS - Nano-scale secondary ion mass spectrometry imaging
- Unit: %.
- Only samples with exogenous carbon amendment were measured.
- Nine spots were analyzed for each sample.
- native_mineral -- The coverages of soil minerals occupied by native OM.
- new_native -- The coverages of native OM occupied by new OC.
Ascomycota - A fungal phylum known as primary decomposers of plant straw
- Unit: %.
- Proportion -- The relative abundance of Ascomycota.
Artificial Soil
- Treatments -- Two artificial soils with different Fe mineral proportions were prepared. The low-Fe artificial soil was composed of 60% sand, 17.5% kaolinite, 17.5% montmorillonite, and 5% goethite (w:w), while the high-Fe artificial soil contained 60% sand, 15% kaolinite, 15% montmorillonite, and 10% goethite (w:w).
- Poly -- The proportion of polysaccharide compounds.
- TOC -- Total organic carbon.
- MNC_f and MNC_b -- Fungal- and bacterial-derived microbial necromass carbon, respectively.
- MNC_t -- Total MNC, which is the sum of MNC_f and MNC_b.
- _SD -- Standard deviation (n = 3).
CO2+PE - CO2 analysis and priming effect (PE) calculation
- Unit for CO2 emissions: mg C kg-1 soil day-1.
- Unit for PE: %.
- Day -- Gas sampling date.
- Flux and Cumulative -- Fluxes and cumulative emissions of CO2.
- PE_inst and PE_cumu -- Instantaneous and cumulative PE.
- _SD -- Standard deviation (n = 3).