Challenges in integrating dissolved organic matter chemodiversity into kinetic models of soil respiration

Journal Article · Thu Aug 28 00:00:00 EDT 2025 · Soil Biology and Biochemistry

DOI:https://doi.org/10.1016/j.soilbio.2025.109954· OSTI ID:3000088

Chakrawal, Arjun ^[1]; Qafoku, Odeta ^[1]; Karra, Satish ^[1]; Bargar, John R. ^[1]; Graham, Emily B. ^[2]

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1. Pacific Northwest National Laboratory (PNNL), Richland, WA (United States). Environmental Molecular Sciences Laboratory (EMSL)
2. Pacific Northwest National Laboratory (PNNL), Richland, WA (United States). Environmental Molecular Sciences Laboratory (EMSL); Washington State Univ., Pullman, WA (United States)

The chemodiversity of dissolved organic matter (DOM) in soil has been proposed to influence the microbial metabolism and fate of belowground organic carbon (C). However, integrating DOM chemistry into soil C cycle models to improve predictions of C stocks and fluxes—beyond simply considering DOM pool size—remains a challenge. While recent research suggests that incorporating DOM chemodiversity into models can improve predictions of microbial respiration, there is still a lack of mechanistic understanding describing how DOM chemodiversity affects microbial metabolism and soil respiration. Here, we evaluated whether DOM chemodiversity was a determinant of soil respiration using paired measurements of high-resolution DOM chemistry, obtained from Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS), and potential soil respiration rates from across the United States (U.S.), all data provided by the Molecular Observation Network. Our objectives were to (1) assess statistical relationships between DOM chemodiversity and microbial respiration, and (2) evaluate the ability of kinetic models to leverage DOM chemistry to explain empirical relationships found in statistical models. Statistical regressions revealed that DOM chemodiversity (alpha diversity) was nonlinearly related to potential soil respiration rates, both independently and through its interactions with DOM and total C concentrations. In soils with relatively high DOM but low total C concentrations, potential soil respiration rates were negatively correlated with DOM alpha diversity, whereas in soils with relatively low DOM and high total C concentrations showed the opposite trend. However, when metabolic transition theory kinetic models were modified to include chemodiversity, their performance was comparable to traditional Monod kinetics approaches, which simulate respiration rates as a function of DOM concentration. The inability to account for nonlinearities in DOM chemodiversity–respiration relationships highlight an opportunity to advance substrate uptake kinetics by establishing causal links between DOM chemodiversity, microbial metabolism trade-offs, and potential interactions under varied environmental conditions.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE Joint Genome Institute (JGI); USDOE Office of Science (SC), Biological and Environmental Research (BER)
• Grant/Contract Number: AC02-05CH11231; AC05-76RL01830
• OSTI ID: 3000088
• Report Number(s): PNNL-SA--206445
• Journal Information: Soil Biology and Biochemistry, Journal Name: Soil Biology and Biochemistry Vol. 211; ISSN 0038-0717
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

Bioenergetic model
Carbon cycle modeling
Chemodiversity
FTICR-MS
Soil organic matter
Soil respiration