Strong priming of soil organic matter induced by frequent input of labile carbon

Labile carbon (C) inputs to soil (e.g., litter and root exudation) can prime soil organic matter (SOM) decomposition, and strongly influence SOM dynamics. The direction and intensity of priming, as well as the net C balance in soil, depend on the amount and frequency of labile C inputs. Most recent priming studies are based on single C additions, which are not truly representative of common litter inputs or root exudation in terrestrial ecosystems. Here, we evaluated the effects of 14C-labeled glucose addition to soil in the same final amounts (360 μg C g−1) split into two temporal patterns: seldom (20% of microbial biomass every two months) and frequent addition (4% of microbial biomass every 10 days) on the dynamics of CO2 production and SOM priming over a 200-day incubation. For the first time, we combined enzyme kinetics with substrate-induced growth respiration and fungal diversity to monitor microbially mediated SOM mineralization in response to the labile C input frequency. Frequent glucose addition decreased 14C incorporation into microbial biomass and almost doubled cumulative priming compared to seldom addition, resulting in a net loss of SOM for seldom and frequent C additions of −94 and −367 μg C g−1 respectively. Larger priming loss of SOM with frequent C inputs was accompanied by increased activities of β-glucosidase, chitinase, and acid phosphatase, and by a shift in fungal community towards increased abundance of K-strategist fungal species (mainly Mortierellales sp. and Trichoderma sp.) capable of SOM mineralization. In conclusion, frequent labile C inputs (e.g., rhizodeposits in rhizosphere or litterfall in disturephere) to soil will stimulate a shift in fungal community structure and functions, resulting in intensive priming of SOM decomposition and CO2 losses. © 2020 Elsevier Ltd

Zhou J.1, 2 , Wen Y.1 , Shi L.2, 3, 4 , Marshall M.R.5 , Kuzyakov Y. 6, 7, 8 , Blagodatskaya E. 8, 9 , Zang H.1
Elsevier Ltd
  • 1 College of Agronomy and Biotechnology, China Agricultural University, Beijing, China
  • 2 Biogeochemistry of Agroecosystems, Department of Crop Science, Georg August University of Göttingen, Göttingen, Germany
  • 3 Key Laboratory of Economic Plants and Biotechnology, Institute of Botany, Chinese Academy of Sciences, Kunming, China
  • 4 World Agroforestry Centre, China & East-Asia Office, Kunming, China
  • 5 School of Natural Sciences, Bangor University, Bangor, Gwynedd LL57 2UW, United Kingdom
  • 6 Department of Soil Science of Temperate Ecosystems, Georg August University of Göttingen, Göttingen, Germany
  • 7 Department of Agricultural Soil Science, Georg August University of Göttingen, Göttingen, Germany
  • 8 Agro-Technological Institute, RUDN University, Moscow, Russian Federation
  • 9 Department of Soil Ecology, Helmholtz Centre for Environmental Research – UFZ, Halle (Saale), Germany
Ключевые слова
Carbon balance; Enzyme kinetics; Fungal community; Microbial growth kinetics; Priming effect; Soil organic matter
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