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Inorganic carbon is overlooked in global soil carbon research: A bibliometric analysis

Raza, Sajjad; Irshad, Annie; Margenot, Andrew; Zamanian, Kazem; Li, Nan; Ullah, Sami; Mehmood, Khalid; Khan, Muhammad Ajmal; Siddique, Nadeem; Zhou, Jianbin; Mooney, Sacha J; Kurganova, Irina; Zhao, Xiaoning; Kuzyakov, Yakov

Inorganic carbon is overlooked in global soil carbon research: A bibliometric analysis Thumbnail


Annie Irshad

Andrew Margenot

Kazem Zamanian

Nan Li

Sami Ullah

Khalid Mehmood

Muhammad Ajmal Khan

Nadeem Siddique

Jianbin Zhou

Professor of Soil Physics

Irina Kurganova

Xiaoning Zhao

Yakov Kuzyakov


Soils are a major player in the global carbon (C) cycle and climate change by functioning as a sink or a source of atmospheric carbon dioxide (CO2). The largest terrestrial C reservoir in soils comprises two main pools: organic (SOC) and inorganic C (SIC), each having distinct fates and functions but with a large disparity in global research attention. This study quantified global soil C research trends and the proportional focus on SOC and SIC pools based on a bibliometric analysis and raise the importance of SIC pools fully underrepresented in research, applications, and modeling. Studies on soil C pools started in 1905 and has produced over 47,000 publications (>1.7 million citations). Although the global C stocks down to 2 m depth are nearly the same for SOC and SIC, the research has dominantly examined SOC (>96 % of publications and citations) with a minimal share on SIC (<4%). Approximately 40 % of the soil C research was related to climate change. Despite poor coverage and publications, the climate change-related research impact (citations per document) of SIC studies was higher than that of SOC. Mineral associated organic carbon, machine learning, soil health, and biochar were the recent top trend topics for SOC research (2020–2023), whereas digital soil mapping, soil properties, soil acidification, and calcite were recent top trend topics for SIC. SOC research was contributed by 151 countries compared to 88 for SIC. As assessed by publications, soil C research was mainly concentrated in a few countries, with only 9 countries accounting for 70 % of the research. China and the USA were the major producers (45 %), collaborators (37 %), and funders of soil C research. SIC is a long-lived soil C pool with a turnover rate (leaching and recrystallization) of more than 1000 years in natural ecosystems, but intensive agricultural practices have accelerated SIC losses, making SIC an important player in global C cycle and climate change. The lack of attention and investment towards SIC research could jeopardize the ongoing efforts to mitigate climate change impacts to meet the 1.5–2.0 °C targets under the Paris Climate Agreement of 2015. This bibliographic study calls to expand the research focus on SIC and including SIC fluxes in C budgets and models, without which the representation of the global C cycle is incomplete.

Journal Article Type Article
Acceptance Date Feb 19, 2024
Online Publication Date Feb 29, 2024
Publication Date 2024-03
Deposit Date Feb 19, 2024
Publicly Available Date Feb 19, 2024
Journal Geoderma
Print ISSN 0016-7061
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 443
Article Number 116831
Keywords Carbon stocks, Climate change, CO2 emission, Soil inorganic carbon, Carbon sequestration, Soil organic carbon, Bibliometric analysis
Public URL
Publisher URL
Additional Information This article is maintained by: Elsevier; Article Title: Inorganic carbon is overlooked in global soil carbon research: A bibliometric analysis; Journal Title: Geoderma; CrossRef DOI link to publisher maintained version:; Content Type: article; Copyright: © 2024 The Author(s). Published by Elsevier B.V.


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