Dynamics of organic matter molecular composition under aerobic decomposition and their response to the nitrogen addition in grassland soils

Qian Zhao, Allison M. Thompson, Stephen J. Callister, Malak M. Tfaily, Sheryl L. Bell, Sarah E. Hobbie, Kirsten S. Hofmockel

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Grassland soils store a substantial proportion of the global soil carbon (C) stock. The transformation of C in grassland soils with respect to chemical composition and persistence strongly regulate the predicted terrestrial-atmosphere C flux in global C biogeochemical cycling models. In addition, increasing atmospheric nitrogen (N) deposition alters C chemistry in grassland soils. However, there remains controversy about the importance of mineralogical versus biochemical preservation of soil C, as well as uncertainty regarding how grassland soil C chemistry responds to elevated N. This study used grassland soils with diverse soil organic matter (SOM) chemistries in an 8-month aerobic incubation experiment to evaluate whether the chemical composition of SOM converged across sites over time, and how SOM persistence responded to the N addition. This study demonstrates that over the course of incubation, the richness of labile compounds decreased in soils with less ferrihydrite content, whereas labile compounds were more persistent in ferrihydrite rich soils. In contrast, we found that the richness of more complex compounds increased over the incubation in most sites, independent of soil mineralogy. Moreover, we demonstrate the extent to which the diverse chemical composition of SOM converged among sites in response to microbial decomposition. N fertilization decreased soil respiration and inhibited the convergence of molecular composition across ecosystems by altering N demand for microbial metabolism and chemical interactions between minerals and organic molecules. This study provides original evidence that the decomposition and metabolism of labile organic molecules were largely regulated by soil mineralogy (physicochemical preservation), while the metabolism of more complex organic molecules was controlled by substrate complexity (biochemical preservation) independent to mineral-organic interactions. This study advanced our understanding of the dynamic biogeochemical cycling of C by unveiling that N addition dampened C respiration and diminished the convergence of SOM chemistry across diverse grassland ecosystems.

Original languageEnglish (US)
Article number150514
JournalScience of the Total Environment
Volume806
DOIs
StatePublished - Feb 1 2022

Bibliographical note

Funding Information:
This work was funded by National Science Foundation (NSF) award to K. S. Hofmockel (NSF-DEB-1556418) and FY16 Laboratory Directed Research and Development program at Pacific Northwest National Laboratory, a multiprogram national laboratory operated by Battelle for the U.S. Department of Energy (DOE) (contract DE-AC05-76RL01830). We thank collaborators from the Nutrient Network (http://nutnet.org) providing us soil property data. We also thank lead investigators, Dana M. Blumenthal (USDA-Agricultural Research Service), Cynthia S. Brown (Colorado State University), Scott L. Collins (University of New Mexico), Julia A. Klein (Colorado State University), Johannes M. H. Knops (University of Nebraska) at each site for operations and maintenance. Coordination and data management of Nutrient Network project have been supported by E. T. Borer, S. E. Hobbie, and E. W. Seabloom from the National Science Foundation Research Coordination Network (NSF-DEB-1042132) and Long-Term Ecological Research (NSF-DEB-1234162 to Cedar Creek LTER) programs, and the UMN Institute on the Environment (DG-0001-13). The research was performed at Environmental Molecular Sciences Laboratory (EMSL), a DOE Office of Science User Facility sponsored by the Office of Biological and Environmental Research. We appreciate the help with graphical editing by Nathan Johnson at Pacific Northwest National Laboratory.

Funding Information:
This work was funded by National Science Foundation (NSF) award to K. S. Hofmockel ( NSF-DEB-1556418 ) and FY16 Laboratory Directed Research and Development program at Pacific Northwest National Laboratory, a multiprogram national laboratory operated by Battelle for the U.S. Department of Energy (DOE) (contract DE-AC05-76RL01830). We thank collaborators from the Nutrient Network ( http://nutnet.org ) providing us soil property data. We also thank lead investigators, Dana M. Blumenthal (USDA-Agricultural Research Service), Cynthia S. Brown (Colorado State University), Scott L. Collins (University of New Mexico), Julia A. Klein (Colorado State University), Johannes M. H. Knops (University of Nebraska) at each site for operations and maintenance. Coordination and data management of Nutrient Network project have been supported by E. T. Borer, S. E. Hobbie, and E. W. Seabloom from the National Science Foundation Research Coordination Network (NSF-DEB-1042132) and Long-Term Ecological Research (NSF-DEB-1234162 to Cedar Creek LTER) programs, and the UMN Institute on the Environment (DG-0001-13). The research was performed at Environmental Molecular Sciences Laboratory (EMSL), a DOE Office of Science User Facility sponsored by the Office of Biological and Environmental Research. We appreciate the help with graphical editing by Nathan Johnson at Pacific Northwest National Laboratory.

Publisher Copyright:
© 2021

Keywords

  • Microbial decomposition
  • Mineral-organic matter association
  • Molecular transformation
  • Nitrogen fertilization
  • Respiration
  • Soil organic matter persistence

Fingerprint

Dive into the research topics of 'Dynamics of organic matter molecular composition under aerobic decomposition and their response to the nitrogen addition in grassland soils'. Together they form a unique fingerprint.

Cite this