TY - JOUR

T1 - Biochar decreased rhizodeposits stabilization via opposite effects on bacteria and fungi

T2 - diminished fungi-promoted aggregation and enhanced bacterial mineralization

AU - Chen, Zhiyi

AU - Kumar, Amit

AU - Fu, Yingyi

AU - Singh, Bhupinder Pal

AU - Ge, Tida

AU - Tu, Hua

AU - Luo, Yu

AU - Xu, Jianming

N1 - Funding Information: This study was supported financially by the National Natural Science Foundation of China (41520104001; 41671233) and the Fundamental Research Funds for the Central Universities (2019QNA6012). The contribution of Amit Kumar was supported by the German Academic Exchange Service (DAAD). We acknowledge the Ningbo Urban Environment Observation and Research Station, Chinese Academy of Sciences for technical assistance. We thank anonymous reviewers and the editor for constructive comments which significantly improved the quality of this paper. Publisher Copyright: © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature.

PY - 2021/5

Y1 - 2021/5

N2 - Ryegrass was pulse-labeled with enriched 13CO2 for 18 h, followed by dynamic photosynthetic-carbon (13C) quantification in the plant (shoot, root), soil aggregates (three size classes), and microbial phospholipids fatty acids (PLFA-SIP) in soil amended with or without 700 °C-pyrolyzed biochar. We observed that biochar led to no difference of 13C allocation in shoot or root but reduced 88.7% of total 13C in soil, with decreased incorporation by 92.8% (macroaggregates), 94.5% (microaggregates), and 84.1% (silt-clays), respectively, compared to biochar-unamended soil. Meanwhile, biochar exerted negative effects on fungal relative abundance but led to positive impacts on that of bacteria, e.g., it reduced root-associated fungi (i.e., 16:1ω5c) and fungal-assimilated 13C (from averagely 71.2 ng C g−1 soil to 26.3 ng C g−1 soil after biochar application). The enhanced bacteria/fungi could be driven by biochar-mediated pH increase that relieved acid stress to bacteria. Co-occurrence network confirmed that biochar addition favored bacteria to compete with fungi, leading to decreased aggregation and stability (indicated by reduced normalized mean weight diameter) due to less fungal entangling with aggregates, thus exposing the rhizodeposits to bacterial (i.e., actinomycetes) decomposition. The correlation analysis further evidenced that fungal abundance was associated with 13C accumulation in soil aggregates, while bacterial relative abundance especially that of actinomycetes was negatively correlated with 13C accumulation. Random forest modeling (RF) supported the contributions of fungi to 13C-sequestration compared to bacteria. Taken together, we concluded that less stabilization of rhizodeposits in the biochar-amended soil was due to changes in microbial community, particularly the balance of fungi-bacteria and their interactions with soil physicochemical properties, i.e., aggregation and pH.

AB - Ryegrass was pulse-labeled with enriched 13CO2 for 18 h, followed by dynamic photosynthetic-carbon (13C) quantification in the plant (shoot, root), soil aggregates (three size classes), and microbial phospholipids fatty acids (PLFA-SIP) in soil amended with or without 700 °C-pyrolyzed biochar. We observed that biochar led to no difference of 13C allocation in shoot or root but reduced 88.7% of total 13C in soil, with decreased incorporation by 92.8% (macroaggregates), 94.5% (microaggregates), and 84.1% (silt-clays), respectively, compared to biochar-unamended soil. Meanwhile, biochar exerted negative effects on fungal relative abundance but led to positive impacts on that of bacteria, e.g., it reduced root-associated fungi (i.e., 16:1ω5c) and fungal-assimilated 13C (from averagely 71.2 ng C g−1 soil to 26.3 ng C g−1 soil after biochar application). The enhanced bacteria/fungi could be driven by biochar-mediated pH increase that relieved acid stress to bacteria. Co-occurrence network confirmed that biochar addition favored bacteria to compete with fungi, leading to decreased aggregation and stability (indicated by reduced normalized mean weight diameter) due to less fungal entangling with aggregates, thus exposing the rhizodeposits to bacterial (i.e., actinomycetes) decomposition. The correlation analysis further evidenced that fungal abundance was associated with 13C accumulation in soil aggregates, while bacterial relative abundance especially that of actinomycetes was negatively correlated with 13C accumulation. Random forest modeling (RF) supported the contributions of fungi to 13C-sequestration compared to bacteria. Taken together, we concluded that less stabilization of rhizodeposits in the biochar-amended soil was due to changes in microbial community, particularly the balance of fungi-bacteria and their interactions with soil physicochemical properties, i.e., aggregation and pH.

KW - C labeling

KW - Aggregation

KW - Biochar

KW - Carbon allocation

KW - PLFA-SIP

KW - Biology

KW - Ecosystems Research

UR - http://www.scopus.com/inward/record.url?scp=85100868021&partnerID=8YFLogxK

U2 - 10.1007/s00374-020-01539-9

DO - 10.1007/s00374-020-01539-9

M3 - Journal articles

AN - SCOPUS:85100868021

VL - 57

SP - 533

EP - 546

JO - Biology and Fertility of Soils

JF - Biology and Fertility of Soils

SN - 0178-2762

IS - 4

ER -