Кл.слова (ненормированные):
Compound-specific 13C-PLFA analysis -- Glucose mineralization -- Necromass recycling -- Priming effects -- Soil carbon -- Stoichiometric imbalance -- Carbon dioxide -- Glucose -- Mineralogy -- Nitrogen -- Recycling -- Soils -- Compound-specific. 3C-PLFA analysis -- Necromass -- Priming effects -- Soil carbon -- Stoichiometric imbalance -- Bacteria -- anoxic conditions -- biomineralization -- carbon isotope -- decomposition -- glucose -- nitrogen -- nutrient cycling -- soil carbon -- soil nitrogen -- soil organic matter -- stoichiometry -- Actinobacteria (class) -- Bacteria (microorganisms) -- Fungi -- Negibacteria -- Posibacteria
Аннотация: The impact of increasing amounts of labile C input on priming effects (PE) on soil organic matter (SOM) mineralization remains unclear, particularly under anoxic conditions and under high C input common in microbial hotspots. PE and their mechanisms were investigated by a 60-day incubation of three flooded paddy soils amended with13C-labeled glucose equivalent to 50–500% of microbial biomass C (MBC). PE (14–55% of unamended soil) peaked at moderate glucose addition rates (i.e., 50–300% of MBC). Glucose addition above 300% of MBC suppressed SOM mineralization but intensified microbial N acquisition, which contradicted the common PE mechanism of accelerating SOM decomposition for N-supply (frequently termed as “N mining”). Particularly at glucose input rate higher than 3 g kg?1 (i.e., 300–500% of MBC), mineral N content dropped on day 2 close to zero (1.1–2.5 mg N kg?1) because of microbial N immobilization. To cope with the N limitation, microorganisms greatly increased N-acetyl glucosaminidase and leucine aminopeptidase activities, while SOM decomposition decreased. Several discrete peaks of glucose-derived CO2 (contributing >80% to total CO2) were observed between days 13–30 under high glucose input (300–500% of MBC), concurrently with CH4 peaks. Such CO2 dynamics was distinct from the common exponential decay pattern, implicating the recycling and mineralization of 13C-enriched microbial necromass driven by glucose addition. Therefore, N recycling from necromass was hypothesized as a major mechanism to alleviate microbial N deficiency without SOM priming under excess labile C input. Compound-specific 13C-PLFA confirmed the redistribution of glucose-derived C among microbial groups, i.e., necromass recycling. Following glucose input, more than 4/5 of total 13C-PLFA was in the gram-negative and some non-specific bacteria, suggesting these microorganisms as r-strategists capable of rapidly utilizing the most labile C. However, their 13C-PLFA content decreased by 70% after 60 days, probably as a result of death of these r-strategists. On the contrary, the 13C-PLFA in gram-positive bacteria, actinomycetes and fungi (K-strategists) was initially minimal but increased by 0.5–5 folds between days 2 and 60. Consequently, the necromass of dead r-strategists provided a high-quality C–N source to the K-strategists. We conclude that under severe C excess, N recycling from necromass is a much more efficient microbial strategy to cover the acute N demand than N acquisition from the recalcitrant SOM. © 2020 Elsevier Ltd
Scopus
Держатели документа:
Key Laboratory of Agro-ecological Processes in Subtropical Region & Changsha Research Station for Agricultural and Environmental Monitoring, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Hunan, 410125, China
State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Gongdong, 510640, China
Jiangsu Provincial Key Laboratory for Bioresources of Coastal Saline Soils, Jiangsu Coastal Biological Agriculture Synthetic Innovation Center, Yancheng Teachers' University, Yancheng, 224002, China
Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China
School of Environment, Natural Resources & Geography, Bangor University, Gwynedd, LL57 2UW, United Kingdom
Department of Agricultural Soil Science, Department of Soil Science of Temperate Ecosystems, University of G?ttingen, G?ttingen, Germany
Institute of Environmental Sciences, Kazan Federal University, Kazan, 420049, Russian Federation
Agro-Technological Institute, RUDN University, Moscow, 117198, Russian Federation
Departamento de Ciencias Quimicas y Recursos Naturales, Universidad de La Frontera, Temuco, Chile
VN Sukachev Institute of Forest, SB-RAS, Krasnoyarsk, 660036, Russian Federation
Доп.точки доступа:
Cui, J.; Zhu, Z.; Xu, X.; Liu, S.; Jones, D. L.; Kuzyakov, Y.; Shibistova, O.; Wu, J.; Ge, T.