Effect of gradual increase of atmospheric CO concentration on nitrification potential and communities of ammonia oxidizers in paddy fields.

Currently, the influence of elevated atmospheric CO concentration (eCO) on ammonia oxidation to nitrite, the rate-limiting step of nitrification in paddy soil, is poorly known. Previous studies that simulate the effect of eCO on nitrification are primarily based on an abrupt increase of atmospheric CO concentration. However, paddy ecosystems are experiencing a gradual increase of CO concentration.

Response of nitrite-dependent anaerobic methanotrophs to elevated atmospheric CO concentration in paddy fields.

Nitrite-dependent anaerobic methane oxidation (n-damo) catalyzed by Candidatus Methylomirabilis oxyfera (M. oxyfera)-like bacteria is a new pathway for the regulation of methane emissions from paddy fields. Elevated atmospheric CO concentrations (e[CO]) can indirectly affect the structure and function of microbial communities.

Different responses of ammonia-oxidizing archaea and bacteria in paddy soils to elevated CO concentration.

The elevated atmospheric CO concentration is well known to have an important effect on soil nutrient cycling. Ammonia oxidation, mediated by ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB), is the rate-limiting step in soil nitrification, which controls the availability of two key soil nutrients (ammonium and nitrate) for crops. Until now, how the AOA and AOB communities in paddy soils respond to elevated CO remains largely unknown.

[Effects of Warming and Straw Application on Soil Microbial Biomass Carbon and Nitrogen and Bacterial Community Structure].

In order to investigate the effects of warming and straw application on soil microbial biomass carbon and nitrogen and bacterial community structure, a randomized block experiment was performed. Four treatments were included, namely a control (CK), warming (WA), straw application (SA), and warming and straw application (WS) treatments. The soils were sampled during the soybean (Sep.

[Effect of different levels of elevated CO concentration on leaf chlorophyll fluorescence cha-racteristics of Japonica rice].

To examine the effects of elevated CO concentrations on chlorophyll fluorescence of rice leaf, a field experiment was conducted with automatic control system of CO concentration in open top-chambers (OTCs). There were three treatments, including atmospheric CO concentration (CK), CK+80 μmol·mol CO (T), and CK+200 μmol·mol CO (T). The fast chlorophyll fluorescence induction dynamic curves of flag leaves were measured using the plant efficiency analyzer at the main growth stages of rice.

[CH Emissions Characteristics and Its Influencing Factors in an Eutrophic Lake].

In order to identify methane (CH) diffusion emissions characteristics and their impact factors in an eutrophic lake, CH flux across the lake-air interface was observed in Meiliang Bay and the central zone of Lake Taihu over one year. The relationships between CH flux and environmental factors and water quality indices were analyzed. The results indicated that the annual mean CH diffusion flux in the eutrophic zone was significantly higher than that in the central zone, which were 0.

[Effects of Simulated Precipitation Reduction on Soil Respiration in a Soybean-Winter Wheat Rotation Cropland].

To investigate the effects of precipitation reduction on soil respiration in rainfed croplands, a field experiment was performed in a soybean-winter wheat cropland. A randomized block design including three treatments, viz. control (CK), 20% precipitation reduction (P20%), and 40% precipitation reduction (P40%), was used.

[Effects of Simulated Acid Rain on Soil Respiration and Heterotrophic Respiration in a Secondary Forest].

In order to investigate the effects of simulated acid rain on soil respiration and heterotrophic respiration in a secondary forest, a field experiment was carried out. A split-plot experiment was arranged in field. There were 4 blocks; each block had two main plots which were trenched and un-trenched plots.

[Effects of Short-time Conservation Tillage Managements on Greenhouse Gases Emissions from Soybean-Winter Wheat Rotation System].

Field experiments including one soybean growing season and one winter-wheat growing season were adopted. The experimental field was divided into four equal-area sub-blocks which differed from each other only in tillage managements, which were conventional tillage (T) , no-tillage with no straw cover ( NT) , conventional tillage with straw cover (TS) , and no-tillage with straw cover (NTS). CO₂ and N₂O emission fluxes from soil-crop system were measured by static chamber-gas chromatograph technique.

[Effects of Warming and Straw Application on Soil Respiration and Enzyme Activity in a Winter Wheat Cropland].

In order to investigate the effects of warming and straw application on soil respiration and enzyme activity, a field experiment was performed from November 2014 to May 2015. Four treatments, which were control (CK), warming, straw application, and warming and straw application, were arranged in field. Seasonal variability in soil respiration, soil temperature and soil moisture for different treatments were measured.

[Effects of Reduced Water and Diurnal Warming on Winter-Wheat Biomass and Soil Respiration].

Field experiments were conducted in winter wheat-growing season to investigate the effect of reduced water and diurnal warming on wheat biomass and soil respiration. The experimental treatments included the control (CK), 30% reduced water (W), diurnal warming (T, enhanced 2 degrees C), and the combined treatment (TW, 30% reduced water plus diurnal warming 2 degrees C). Soil respiration rate was measured using a static chamber-gas chromatograph technique.

[Soil Microbial Respiration Under Different Soil Temperature Conditions and Its Relationship to Soil Dissolved Organic Carbon and Invertase].

In order to investigate the soil microbial respiration under different temperature conditions and its relationship to soil dissolved organic carbon ( DOC) and invertase, an indoor incubation experiment was performed. The soil samples used for the experiment were taken from Laoshan, Zijinshan, and Baohuashan. The responses of soil microbial respiration to the increasing temperature were studied.

[Multi-year measurement of soil respiration components in a subtropical secondary forest].

A four-year field experiment was performed from March 2010 to February 2014 in order to investigate the contribution of different respiratory components to soil respiration and the temperature sensitivity of different respiratory components. Four blocks were arranged in field, and there were trenched and un-trenched plots in each block. Trenching, which can exclude roots, was performed around the trenched plots.

[Impacts of elevated ozone concentration on N2O emission from arid farmland].

To investigate the impact of elevated surface ozone (O3) concentration on nitrous oxide (N2O) emission from arid farmland, field experiments were carried out during winter-wheat and soybean growing seasons under the condition of simulating O3 concentrations, including free air (CK), 100 nL x L(-1) O3 concentration (T1), and 150 nL x L(-1) O3 concentration (T2). N2O emission fluxes were measured by static dark chamber-gas chromatograph method. The results showed that the accumulative amount of N2O (AAN) were decreased by 37.

[Factors influencing the variability in soil heterotrophic respiration from terrestrial ecosystem in China].

Soil heterotrophic respiration is one of the key factors for estimating ecosystem carbon balance. Measurement data of soil heterotrophic respiration from terrestrial ecosystem in China were collected. Climate data (annual precipitation and annual mean air temperature) and relevant environmental factors (e.

[Effects of diurnal warming on soil N2O emission in soybean field].

To investigate the impact of experimental warming on N2O emission from soil of soybean field, outdoor experiments with simulating diurnal warming were conducted, and static dark chamber-gas chromatograph method was used to measure N2O emission fluxes. Results indicated that: the diurnal warming did not change the seasonal pattern of N2O emissions from soil. In the whole growing season, comparing to the control treatment (CK), the warming treatment (T) significantly enhanced the N2O flux and the cumulative amount of N2O by 17.

[Factors influencing the spatial variability in soil respiration under different land use regimes].

In order to investigate the factors influencing the spatial variability in soil respiration under different land use regimes, field experiments were performed. Soil respiration and relevant environment, vegetation and soil factors were measured. The spatial variability in soil respiration and the relationship between soil respiration and these measured factors were investigated.

[Review of the factors influencing the temporal and spatial variability of soil respiration in terrestrial ecosystem].

Soil respiration is an important process in carbon cycling. Understanding the processes and controlling factors of soil respiration are crucial in investigating the terrestrial carbon cycling. This article reviews the investigations about the factors controlling the temporal and spatial variability of soil respiration.

[Impacts of enhanced UV-B radiation on respiration rate, CH4 and N2O emission fluxes from rice paddy].

To investigate the impacts of enhanced UV-B radiation on respiration rate, CH4 and N2O emission fluxes from soil-rice system, outdoor pot experiment was carried out during the rice growing season in 2004. The enhanced UV-B radiation treatments were simulated by a 20% increase in its intensity. The gas emission fluxes were measured by static chamber-gas chromatograph method.

[Effects of elevated ozone concentration on CO2 emission from soil-winter wheat system].

To investigate the impact of elevated ozone (O3) on CO2 emission from soil-winter wheat system, outdoor experiments with simulating elevated O3 concentration were conducted, and static dark chamber-gas chromatograph method was used to measure CO2 emission fluxes. Results indicated that the elevated O3 did not change the seasonal pattern of CO2 emissions from soil-winter wheat system, but significantly decreased CO2 emission fluxes during turning-green stage and elongation-pregnant stage. From heading to maturity, CO2 emission fluxes were not found to be significant difference under 100 nL x L(-1) O3 treatment compared with the control, while 150 nL x L(-1) O3 treatment significantly declined CO2 emission fluxes.

[Effects of elevated ozone concentration on soil respiration, nitrification and denitrification in a winter wheat farmland].

Field experiments were carried out in a winter wheat farmland, in order to investigate the effects of elevated ozone concentration on soil respiration, nitrification and denitrification. Three ozone concentration treatments, which were CK, T1 (100 nL x L(-1)) and T2 (150 nL x L(-1)), were arranged using open top chambers (OTCs). A portable soil CO2 fluxes system was used to measure soil respiration rates.