Labile carbon matters more than temperature for enzyme activity in paddy soil

Global warming increases belowground carbon (C)input as plant litterfall, root biomass and rhizodeposition, which influences the stocks and dynamics of soil organic matter. To clarify the effects of labile C availability (biochemical factor)and temperature (environmental factor)on enzyme activities, we incubated typical paddy soil for 75 d at four temperatures (5, 15, 25, and 35 °C)under anaerobic conditions. Acetate was used as the source of labile C and methane. The potential activities of three hydrolases (β-glucosidase, chitinase, and xylanase)were analysed on days 3, 15, and 75 after acetate addition. Activity of β-glucosidase and chitinase in soil without acetate addition was 2.1–2.7 times higher than that with acetate. Xylanase activity increased with temperature and incubation period. The enzymes involved in the C cycle were sensitive to temperature, whereas chitinase (responsible for N cycle)activity became temperature sensitive only after acetate addition (Q10-Vmax ≥ 1). Organic C mineralisation (CO2 release)was more sensitive at low temperature with Q10 values 1.1–3.4 times higher at 5–15 °C than at 25–35 °C. The Q10 values for methane (CH4)emission were 2.8–13.5 times higher at 5–15 °C than at 25–35 °C. Organic matter decomposition in paddy soil was more sensitive to temperature (Q10 of CO2 and CH4 emission ≥ 1)than enzyme activities. Comparison of abiotic (temperature)and biochemical (C availability)effects indicated that warming has limited effects on hydrolase activities in paddy soil. The increase in labile C remarkably stimulated microbial activity and soil organic matter turnover. We conclude that: i)enzyme activities are more sensitive to C addition than to temperature; ii)and SOM decomposition is accelerated by both C input and warming, especially at low temperatures. © 2019 Elsevier Ltd

Wei L.1, 2 , Razavi B.S.1, 3, 4 , Wang W.5 , Zhu Z.1 , Liu S.1 , Wu J.1, 2 , Kuzyakov Y. 6, 7, 8, 9 , Ge T.1
Elsevier Ltd
  • 1 Key Laboratory of Agro-ecological Processes in Subtropical Region and Changsha Research Station for Agricultural and Environmental Monitoring & Institute of Subtropical Agriculture, Chinese Academy of SciencesHunan 410125, China
  • 2 University of Chinese Academy of Sciences, Beijing, 100049, China
  • 3 Institute of Plant Nutrition and Soil Science, Kiel university, Kiel, Germany
  • 4 Institute of Phytopathology, Kiel university, Kiel, Germany
  • 5 Institute of Geography and Key Laboratory of Humid Subtropical Eco-geographical Process, Ministry of Education, Fujian Normal University, Fuzhou, 350007, China
  • 6 Institute of Environmental Sciences, Kazan Federal University, Kazan, 420049, Russian Federation
  • 7 Agro-Technological Institute, RUDN University, Moscow, 117198, Russian Federation
  • 8 Department of Soil Science of Temperate Ecosystems, Department of Agricultural Soil Science, University of Goettingen, Göttingen, Germany
  • 9 Departamento de Ciencias Químicas y Recursos Naturales, Universidad de La Frontera, Temuco, Chile
Ключевые слова
Carbon availability; Hydrolase activities; Methane production; Microbial biomass; Soil organic matter decomposition; Temperature effects
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