ORIGINAL RESEARCH article

Front. Microbiol.

Sec. Terrestrial Microbiology

Volume 16 - 2025 | doi: 10.3389/fmicb.2025.1589966

This article is part of the Research TopicSoil Carbon Sequestration and Microbial Energy MetabolismView all 6 articles

Soil microbial necromass carbon contributions to soil organic carbon after three decades of citrus cultivation

Provisionally accepted
Tangyingze  MeiTangyingze Mei1QUANCHAO  ZENGQUANCHAO ZENG2*Ruifeng  ChenRuifeng Chen2Wenfeng  TanWenfeng Tan1
  • 1Huazhong Agricultural University, Wuhan, Hubei Province, China
  • 2Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences (CAS), Chongqing, China

The final, formatted version of the article will be published soon.

Citrus is one of the most economically significant fruits globally, and soil organic carbon (SOC) plays a central role in maintaining soil health and fertility.Consequently, enhancing SOC content directly influences both the yield and quality of citrus crops. However, the sources of SOC in citrus orchards and their mechanisms of contribution remains poorly understood. This study investigated citrus soils from orchards of varying planting ages by collecting 0-20 cm soil samples. We analyzed amino sugars, glomalin, particulate organic carbon (POC), and mineral-bound organic carbon (MAOC) to examine the source of microbial residue carbon and its contribution to SOC. The results revealed a significant decrease in microbial residue carbon (MNC), fungal residue carbon (FNC), and bacterial residue carbon (BNC) with increasing orchard age (P < 0.05). Specifically, the MNC in 30-year-old citrus soils was reduced by 46.27% compared to 10-year-old soils, FNC decreased by 45.61%, and BNC by 48.91%. The proportion of microbial residue carbon within SOC significantly decreased as planting years increased (P < 0.05), from 76.82 ± 2.84% in 10-year-old citrus soils to 20.54 ± 4.70% in 30-year-old soils. Furthermore, soil pH, NO₃ --N and MAOC were the main factors controlling MNC. MNC showed a significant negative correlation with SOC, indicating a weakened microbial carbon pump function in citrus soils and an increased reliance on other carbon sources, such as plant-derived carbon. Although citrus cultivation had led to a decline in microbial residue carbon over time, it remained a primary source of organic carbon, with its contribution depending on the age of the orchard. These findings offered novel insights into the mechanisms through which intensive citrus cultivation influences microbial necromass contributions to SOC. This study also highlighted the negative impacts of long-term citrus cultivation on soil microbial necromass and offered recommendations for the rehabilitation of aging orchards.

Keywords: Soil Organic Carbon, Citrus planted years, Microbial-associated organic carbon, microbial necromass carbon, Forest

Received: 08 Mar 2025; Accepted: 23 Apr 2025.

Copyright: © 2025 Mei, ZENG, Chen and Tan. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: QUANCHAO ZENG, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences (CAS), Chongqing, China

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