Short-Term Response of the Soil Microbial Abundances and Enzyme Activities to Experimental Warming in a Boreal Peatland in Northeast China

Abstract

Global warming is likely to influence the soil microorganisms and enzyme activity and alter the carbon and nitrogen balance of peatland ecosystems. To investigate the difference in sensitivities of carbon and nitrogen cycling microorganisms and enzyme activity to warming, we conducted three-year warming experiments in a boreal peatland. Our findings demonstrated that both mcrA and nirS gene abundance in shallow soil and deep soil exhibited insensitivity to warming, while shallow soil archaea 16S rRNA gene and amoA gene abundance in both shallow soil and deep soil increased under warming. Soil pmoA gene abundance of both layers, bacterial 16S rRNA gene abundance in shallow soil, and nirK gene abundance in deep soil decreased due to warming. The decreases of these gene abundances would be a result of losing labile substrates because of the competitive interactions between aboveground plants and underground soil microorganisms. Experimental warming inhibited β-glucosidase activity in two soil layers and invertase activity in deep soil, while it stimulated acid phosphatase activity in shallow soil. Both temperature and labile substrates regulate the responses of soil microbial abundances and enzyme activities to warming and affect the coupling relationships of carbon and nitrogen. This study provides a potential microbial mechanism controlling carbon and nitrogen cycling in peatland under climate warming.

Temporal Impacts of Different Fertilization Systems on Soil Health under Arid Conditions of Potato Monocropping

“…In contrast, this study revealed that soil microbial biomass nitrogen (N mic ) values were identical and not significantly correlated with soil properties of SOC (R 2 = 0.0001) or DOC (R 2 = 0.0002) indicating lower microbial and enzyme activities. On the contrary to DOC, inorganic fertilization system enhanced DON levels in the soil under investigation reflected by positive correlation between N mic and DON (r = 0.57) and these positive effects have been demonstrated in many literatures (Dinesh et al 2013;Jian et al 2016;Song et al 2019). DON is used as a measure of labile substrate N for soil microorganisms nutrition exactly as labile C as measured by dissolved organic carbon (DOC), even though weak correlation was observed between DOC and DON (r = 0.1; p < 0.05; n = 20).…”

“…The counts of bacteria and fungi were also more prominent in organic than in integrated at all application rates. Results of this study suggest that the temporal growth of soil microbial biomass may be either partially inhibited or completely facilitated following a fertilization system, depending on fertilizer type and application rate (Anderson and Domsch 2010;Jian et al 2016;Song et al 2019).…”

“…Different fertilization systems obviously affected dissolved soil organic substrates (DOC and DON) and soil levels of SOC, though at varying degrees according to each fertilizer type. A fertilizer type and rate effect upon soil biochemical properties is well established in the literature by many researchers (Wang et al 2008;Rifai et al 2010;Dinesh et al 2013;Jian et al 2016;Song et al 2019). Founded on this research, it is preferable to integrate organic compost plus NPK nanofertilizers on fertilizers due to the priority of lower rates of nanofertilizers on a full dose of NPK fertilizers (El-Sharkawy et al 2017;Burhan and AL-Hassan 2019).…”

“…Evident effects of different fertilization systems on net N min levels indicate increases in soil microbial population pool (Dinesh et al 2013;Jian et al 2016;Song et al 2019). Greater levels of N min in organic and integrated treatments indicated that more nutrient and organic carbon availability imparted favorable conditions for soil microorganisms reflexed on increases in the counts of bacteria and fungi and fast nutrient turnover (Rivest et al 2010;Jian et al 2016).…”

“…Organic carbon and carbon storage in agricultural soils are the major and most labile carbon pools on the earth's mantle ecosystem, and CO 2 exchange between agricultural soils ecosystems and the atmosphere has a significant impact on the carbon cycle in soils (Yang et al 2018;Song et al 2019). Among significant factors affecting net soil ecosystem CO 2 exchange and soil organic carbon (SOC) and storage is the fertilization type and method applied (Liu et al 2016;Yang et al 2018).…”