The Emissions of Carbon Dioxide, Methane, and Nitrous Oxide during Winter without Cultivation in Local Saline-Alkali Rice and Maize Fields in Northeast China

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.

Section: Response Of Soil C and N Contents To Experimental Warmingmentioning

confidence: 66%

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

Song

Ren

et al. 2019

“…The annual mean temperature is about 4.5 • C, the lowest temperature is in January (the extreme minimum temperature −36.1 • C), and the highest temperature is in July (the extreme maximum temperature 37 • C). Annual precipitation is between 400 mm and 500 mm [32].…”

Section: Study Sites and Sampling Designmentioning

confidence: 99%

“…The annual mean temperature is about 4.5 °C, the lowest temperature is in January (the extreme minimum temperature -36.1 °C), and the highest temperature is in July (the extreme maximum temperature 37 °C). Annual precipitation is between 400 mm and 500 mm [32]. Four plots (P1, P2, P3, and P4) with different saline-alkali stresses were selected after preexperiments and initial data analysis of the project (Table 1).…”

Section: Study Sites and Sampling Designmentioning

confidence: 99%

Carbon Mineralization under Different Saline—Alkali Stress Conditions in Paddy Fields of Northeast China

Wang

Tang

et al. 2020

Self Cite

Soil organic carbon (SOC) mineralization (conversion of carbonaceous material to carbon dioxide) plays a central role in global carbon cycle. However, the effects of SOC mineralization under different saline–alkali stress conditions are poorly understood. In order to understand the carbon mineralization processes, four paddy fields with different saline and alkali degrees were chosen as the experimental samples and the soil CO2 emission fluxes at nine different time steps of the whole simulation experiment were observed. The physical and chemical properties of soils of four field conditions were compared for the dynamic changes of CO2 flux in the progress of paddy field cultivation simulations. The results showed that the first three fields (P1, P2, and P3) were weakly alkaline soils and the last one (P4) was strongly alkaline soil. The SOC content of each plot was significantly different and there was a near-surface enrichment, which was significantly negatively correlated with the degree of alkalization. The accumulation process of the SOC mineralization during the incubation time was consistent with the first-order kinetic model. In the initial stage of mineralization, the amount of CO2 released massively, and then the release intensity decreased rapidly. The mineralization rate decreased slowly with time and finally reached a minimum at the end of the incubation period. This study indicates that the SOC mineralization process is affected by a variety of factors. The main factors influencing SOC mineralization in the saline–alkaline soils are the exchangeable sodium percentage (ESP), followed by enzyme activities. Salinization of the soils inhibits the rate of soil carbon cycle, which has a greater impact on the carbon sequestration than on the carbon source process. The intensity and completeness of the SOC mineralization reactions increase with increasing SOC contents and decrease with increasing ESP levels.

“…Global warming is receiving more and more attention because of the series of threats it poses, like sea-level rise, land area decline, extreme climates, and food supply shortages, which challenge the sustainable development of eco-environments and social economy [1]. Greenhouse gas (GHG) emissions, including carbon dioxide (CO 2 ), methane (CH 4 ), and nitrous oxide (N 2 O), are responsible for global warming, owing to the greenhouse effects.…”

Section: Introductionmentioning

confidence: 99%

“…SIC is classified as two central units stored in soil, namely, lithogenic inorganic carbon (LIC), inheriting from the parent material, and pedogenic inorganic carbon (PIC), resulting from the precipitation of carbonate ions. The formation of pedogenic carbonate, shown in Equations (1) and (2), can either be a source or sink of C [16]. In the input or output of soil, C is transformed in the process of precipitation.…”

Section: Introductionmentioning

confidence: 99%

Corn and Rice Cultivation Affect Soil Organic and Inorganic Carbon Storage through Altering Soil Properties in Alkali Sodic Soils, Northeast of China

Wang

Tang

et al. 2020

Self Cite

Soil organic carbon (SOC) and soil inorganic carbon (SIC) play essential roles in carbon cycling in terrestrial ecosystems; however, the effects of crop cultivation on them are still poorly understood, especially in alkali sodic soils widely distributed in semiarid regions. Alkali sodic soils from cornfields and paddies with cultivation years of 5, 15, and 25 were analyzed here to assess the response of soil properties and soil carbon pools to crop cultivation. Soil pH and exchangeable sodium percentages decrease in accordance with cultivation years, while enzyme activity (amylase, invertase, and catalase) shows a contrary trend. Soil pH and exchangeable sodium percentages are negatively correlated with SOC, but positively correlated with SIC. Redundancy analysis reveals an obvious relationship between SOC and invertase activity. The percentage of δ 13 C SOC found here is approximately -24.78% to -22.97% for cornfields and approximately -26.54% to -23.81% for paddies, suggesting that crop cultivation contributes to SOC sequestration and stocking, increasing with cultivation years. The percentage of δ 13 C SIC found here is approximately 1.90% to 3.73% , proving that lithogenic inorganic carbon is the major SIC, where the stock decreases with increasing cultivation years. Significant total carbon stock loss is observed in cornfields, while it is preserved at 120 Mg ha −1 in paddies. We conclude here from the results that corn and rice cultivation reduce alkali sodic conditions in soil, thereby improving soil enzymes and favoring SOC stocking, but reducing SIC stocks.