Labile carbon matters more than temperature for enzyme activity in paddy soil. (August 2019)

• Record Type: Journal Article
• Authors: Wei, Liang; Razavi, Bahar S.; Wang, Weiqi; Zhu, Zhenke; Liu, Shoulong; Wu, Jinshui; Kuzyakov, Yakov; Ge, Tida
• Is Part Of: Soil biology and biochemistry. Volume 135(2019)
• Page Start: 134
• Page End: 143
• Publication Date: 2019-08
• Subjects: Carbon availability -- Hydrolase activities -- Methane production -- Microbial biomass -- Soil organic matter decomposition -- Temperature effects; Soil biochemistry -- Periodicals; Soil biology -- Periodicals; Sols -- Biochimie -- Périodiques; Sols -- Biologie -- Périodiques; Sols -- Microbiologie -- Périodiques; Bodembiologie; Biochemie; 631.46
• DOI: 10.1016/j.soilbio.2019.04.016
• Languages: English
• ISSNs: 0038-0717

Abstract

Abstract: 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 ( Q 10 - V max ≥ 1). Organic C mineralisation (CO2 release) was more sensitive at low temperature with Q 10 values 1.1–3.4 times higher at 5–15 °C than at 25–35 °C. The Q 10 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 ( Q 10 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. Graphical abstract: Image 1 Highlights: Labile C affects the response of extracellular enzyme activities to soil warming. The higher the labile C content, the less enzymes are produced by soil microorganisms. Labile C addition affects microbial biomass and induces enzymatic N mining from SOM. Acetate input increases temperature sensitivity of CO2 and CH4 emission below 15 °C.