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1.
Soil faunal activity can be a major control of greenhouse gas (GHG) emissions from soil. Effects of single faunal species, genera or families have been investigated, but it is unknown how soil fauna diversity may influence emissions of both carbon dioxide (CO 2, end product of decomposition of organic matter) and nitrous oxide (N 2O, an intermediate product of N transformation processes, in particular denitrification). Here, we studied how CO 2 and N 2O emissions are affected by species and species mixtures of up to eight species of detritivorous/fungivorous soil fauna from four different taxonomic groups (earthworms, potworms, mites, springtails) using a microcosm set‐up. We found that higher species richness and increased functional dissimilarity of species mixtures led to increased faunal‐induced CO 2 emission (up to 10%), but decreased N 2O emission (up to 62%). Large ecosystem engineers such as earthworms were key drivers of both CO 2 and N 2O emissions. Interestingly, increased biodiversity of other soil fauna in the presence of earthworms decreased faunal‐induced N 2O emission despite enhanced C cycling. We conclude that higher soil fauna functional diversity enhanced the intensity of belowground processes, leading to more complete litter decomposition and increased CO 2 emission, but concurrently also resulting in more complete denitrification and reduced N 2O emission. Our results suggest that increased soil fauna species diversity has the potential to mitigate emissions of N 2O from soil ecosystems. Given the loss of soil biodiversity in managed soils, our findings call for adoption of management practices that enhance soil biodiversity and stimulate a functionally diverse faunal community to reduce N 2O emissions from managed soils. 相似文献
2.
凋落物既是森林生态系统养分循环的重要构件,又是森林土壤环境和功能的关键调节因子。降雨脉冲导致的土壤碳排放变异是陆地生态系统碳汇能力评价的不确定性来源之一。凋落物在调节土壤碳排放对降雨脉冲的响应中的作用仍缺乏科学的评价。通过在暖温带栎类落叶阔叶林中设置不同凋落物处理(对照、去除凋落物和加倍凋落物)和降雨模拟实验以阐明凋落物数量变化对土壤呼吸脉冲的影响。结果表明:模拟降雨脉冲之前,不同凋落物处理下的土壤呼吸存在显著差异;与对照相比,加倍凋落物导致土壤呼吸速率显著增加57.6%,然而,去除凋落物则对土壤呼吸无显著影响。模拟降雨后52小时内,对照、去除凋落物和加倍凋落物样方的土壤累积碳排放量分别为251.69 gC/m~2,250.93 gC/m~2和409.01 gC/m~2,加倍凋落物处理下的土壤碳排放量显著高于对照和去除凋落物处理;然而,去除凋落物与对照之间无显著差异。此外,不同凋落物处理下土壤呼吸的脉冲持续时间存在显著差异;加倍凋落物显著提高降雨后土壤呼吸脉冲的持续时间,分别比对照和去除凋落物高出262%和158%。多元逐步回归分析表明,土壤总碳排放通量和土壤呼吸的脉冲持续时间与土壤理... 相似文献
3.
Background and aimsThe litter layer is a major source of CO2, and it also influences soil-atmosphere exchange of N2O and CH4. So far, it is not clear how much of soil greenhouse gas (GHG) emission derives from the litter layer itself or is litter-induced. The present study investigates how the litter layer controls soil GHG fluxes and microbial decomposer communities in a temperate beech forest. MethodsWe removed the litter layer in an Austrian beech forest and studied responses of soil CO2, CH4 and N2O fluxes and the microbial community via phospholipid fatty acids (PLFA). Soil GHG fluxes were determined with static chambers on 22 occasions from July 2012 to February 2013, and soil samples collected at 8 sampling events. ResultsLitter removal reduced CO2 emissions by 30 % and increased temperature sensitivity (Q10) of CO2 fluxes. Diffusion of CH4 into soil was facilitated by litter removal and CH4 uptake increased by 16 %. This effect was strongest in autumn and winter when soil moisture was high. Soils without litter turned from net N2O sources to slight N2O sinks because N2O emissions peaked after rain events in summer and autumn, which was not the case in litter-removal plots. Microbial composition was only transiently affected by litter removal but strongly influenced by seasonality. ConclusionsLitter layers must be considered in calculating forest GHG budgets, and their influence on temperature sensitivity of soil GHG fluxes taken into account for future climate scenarios. 相似文献
4.
线虫和蚯蚓是农业中广泛存在的土壤动物,由于它们与微生物的相互作用及对土壤生态系统能量传递和养分转化的影响,可能影响土壤微量气体代谢和温室气体的排放.通过在不同土壤线虫密度下接种蚯蚓的15d培养试验结果表明,土壤动物对土壤微量气体(CO2和N2O)代谢有显著促进作用.与灭线土相比,高密度线虫土壤处理与高密度线虫土壤加蚯蚓的处理导致CO2排放量分别增加了4.3倍和5.2倍,相应的N2O排放量增加了1.8倍和2.7倍.与低密度线虫土壤处理比较时,高密度线虫土壤处理导致CO2和N2O排放量分别增加了19%和21%.接种蚯蚓在高密度线虫土中较接种在低密度线虫土壤中的CO2和N2O排放量分别增加了12%和27%.5个处理中,除了低密度线虫加蚯蚓的处理和高密度线虫处理间差异不显著外,其余各处理间均达到极显著差异(P<0.01).两种气体的排放速率呈极显著正相关(R2=0.9414).高密度线虫土壤较低密度线虫土壤显著提高了土壤的DOC含量,不同线虫密度土壤中DOC显著性的差异与CO2和N2O排放密切相关(P<0.05). 相似文献
5.
Carbon (C) sequestration potential of biochar should be considered together with emission of greenhouse gases when applied to soils. In this study, we investigated CO 2 and N 2O emissions following the application of rice husk biochars to cultivated grassland soils and related gas emissions tos oil C and nitrogen (N) dynamics. Treatments included biochar addition (CHAR, NO CHAR) and amendment (COMPOST, UREA, NO FERT). The biochar application rate was 0.3% by weight. The temporal pattern of CO 2 emissions differed according to biochar addition and amendments. CO 2 emissions from the COMPOST soils were significantly higher than those from the UREA and NO FERT soils and less CO 2 emission was observed when biochar and compost were applied together during the summer. Overall N 2O emission was significantly influenced by the interaction between biochar and amendments. In UREA soil, biochar addition increased N 2O emission by 49% compared to the control, while in the COMPOST and NO FERT soils, biochar did not have an effect on N 2O emission. Two possible mechanisms were proposed to explain the higher N 2O emissions upon biochar addition to UREA soil than other soils. Labile C in the biochar may have stimulated microbial N mineralization in the C-limited soil used in our study, resulting in an increase in N 2O emission. Biochar may also have provided the soil with the ability to retain mineral N, leading to increased N 2O emission. The overall results imply that biochar addition can increase C sequestration when applied together with compost, and might stimulate N 2O emission when applied to soil amended with urea. 相似文献
6.
农田土壤是温室气体的重要排放源,溶解性有机物作为土壤微生物容易利用的基质,其含量变化与温室气体的产生和排放密切相关。基于室内培养试验,对溶解性有机物影响土壤CO2、N2O的排放过程进行了分析。设置空白(CK)、单施秸秆(S)、单施氮肥(N)、秸秆和氮肥(S+N)4个不同的处理,对添加不同物质条件下土壤溶解性有机碳(DOC)、溶解性有机氮(DON)和CO2、N2O的排放动态进行了研究,对DOC和DON影响CO2、N2O的排放过程进行了探讨。结果表明:不同处理的温室气体排放通量和土壤DOC、DON含量差异显著;各处理的CO2排放通量和DOC动态随培养时间的延长呈现逐渐减小的趋势,S和S+N处理的N2O排放和DON动态呈现先增大后减小的趋势;S+N处理的CO2排放量最高,DON含量也显著高于其他处理,单施秸秆(S)处理的N2O排放量和DOC含量显著高于其它处理,单施氮肥(N)对土壤CO2的排放量和DOC含量的影响较小;土壤CO2和N2O的排放通量与土壤DOC和DON含量呈显著的相关性,相关系数(R2)达0.6以上,说明溶解性有机物的含量和动态对CO2、N2O的排放过程产生显著影响。 相似文献
7.
Modelling of soil emissions of nitrous oxide (N 2O) and carbon dioxide (CO 2) is complicated by complex interactions between processes and factors influencing their production, consumption and transport. In this study N 2O emissions and heterotrophic CO 2 respiration were simulated from soils under winter wheat grown in three different organic and one inorganic fertilizer-based cropping system using two different models, i.e., MoBiLE-DNDC and FASSET. The two models were generally capable of simulating most seasonal trends of measured soil heterotrophic CO 2 respiration and N 2O emissions. Annual soil heterotrophic CO 2 respiration was underestimated by both models in all systems (about 10?C30% by FASSET and 10?C40% by MoBiLE-DNDC). Both models overestimated annual N 2O emissions in all systems (about 10?C580% by FASSET and 20?C50% by MoBiLE-DNDC). In addition, both models had some problems in simulating soil mineral nitrogen, which seemed to originate from deficiencies in simulating degradation of soil organic matter, incorporated residues of catch crops and organic fertilizers. To improve the performance of the models, organic matter decomposition parameters need to be revised. 相似文献
8.
以华北农田冬小麦-夏玉米轮作体系连续6a施用生物炭和秸秆还田的土壤为研究对象,于2013年10月—2014年9月,采用静态暗箱-气相色谱法,对CO_2、N_2O通量进行了整个轮作周期的连续观测,探究施用生物炭与秸秆还田对其排放通量的影响。试验共设4个处理:CK(对照)、C1(低量生物炭4.5 t hm~(-2)a~(-1))、C2(高量生物炭9.0 t hm~(-2)a~(-1))和SR(秸秆还田straw return)。结果表明:在整个轮作周期内,各处理CO_2、N_2O通量随时间的变化趋势基本一致。随着生物炭施用量的增加,CO_2排放通量分别增加了0.3%—90.3%(C1)、1.0%—334.2%(C2)和0.4%—156.3%(SR)。其中,C2处理对CO_2累积排放量影响最大,增幅为42.9%。对N_2O而言,C2处理显著降低了N_2O累积排放量,但增加了CO_2和N_2O排放的综合增温潜势,C1和SR处理对N_2O累积排放量及综合增温潜势均没有显著影响。相关分析表明,土壤温度和土壤含水量是影响CO_2通量最主要的因素,两者之间呈极显著的正相关关系;N_2O通量与土壤温度、土壤含水量、NO_3~--N和NH_4~+-N均表现出极显著的正相关关系,而与土壤p H值表现出极显著的负相关关系。由此可见,添加生物炭对于减少氮素的气体损失具有较大的潜力。 相似文献
9.
Greenhouse gases (GHG) can be affected by grazing intensity, soil, and climate variables. This study aimed at assessing GHG emissions from a tropical pasture of Brazil to evaluate (i) how the grazing intensity affects the magnitude of GHG emissions; (ii) how season influences GHG production and consumption; and (iii) what are the key driving variables associated with GHG emissions. We measured under field conditions, during two years in a palisade-grass pasture managed with 3 grazing intensities: heavy (15 cm height), moderate (25 cm height), and light (35 cm height) N 2O, CH 4 and CO 2 fluxes using static closed chambers and chromatographic quantification. The greater emissions occurred in the summer and the lower in the winter. N 2O, CH 4, and CO 2 fluxes varied according to the season and were correlated with pasture grazing intensity, temperature, precipitation, % WFPS (water-filled pores space), and soil inorganic N. The explanatory variables differ according to the gas and season. Grazing intensity had a negative linear effect on annual cumulative N 2O emissions and a positive linear effect on annual cumulative CO 2 emissions. Grazing intensity, season, and year affected N 2O, CH 4, and CO 2 emissions. Tropical grassland can be a large sink of N 2O and CH 4. GHG emissions were explained for different key driving variables according to the season. 相似文献
10.
Intensive vegetable production exhibits contrasting characteristics of high nitrous oxide (N 2O) emissions and low nitrogen use efficiency (NUE). In an effort to mitigate N 2O emissions and improve NUE, a field experiment with nine consecutive vegetable crops was designed to study the combined effects of nitrogen (N) and biochar amendment and their interaction on soil properties, N 2O emission and NUE in an intensified vegetable field in southeastern China. We found that N application significantly increased N 2O emissions, N 2O–N emission factors and yield‐scaled N 2O emissions by 51–159%, 9–125% and 14–131%, respectively. Moreover, high N input significantly decreased N partial factor productivity (PFPN) and even yield during the seventh to ninth vegetable crops along with obvious soil degradation and mineral N accumulation. To the contrary, biochar amendment resulted in significant decreases in cumulative N 2O emissions, N 2O–N emission factor and yield‐scaled N 2O emissions by 5–39%, 16–67% and 14–53%, respectively. In addition, biochar significantly increased yield, PFPN and apparent recovery of N (ARN). Although without obvious influence during the first to fourth vegetable crops, biochar amendment mitigated N 2O emissions during the fifth to ninth vegetable crops. The relative effects of biochar amendments were reduced with increasing N application rate. Hence, while high N input produced adverse consequences such as mineral N accumulation and soil degradation in the vegetable field, biochar amendment can be a beneficial agricultural strategy to mitigate N 2O emissions and improve NUE and soil quality in vegetable field. 相似文献
11.
Soil organic carbon (SOC) mineralization is an important process of carbon (C) cycling and budgeting associated with litter decomposition in terrestrial ecosystems. Research on altered plant-derived C input on soil C stability due to climate change is controversial and there remains considerable uncertainty in predicting soil C dynamics with the techniques currently available. In this study, we conducted a laboratory incubation experiment to test the effects of single- and mixed- Deyeuxia angustifolia (DA) and Carex lasiocarpa (CL) leaf litter addition on cumulative marshland soil CO 2 emission under waterlogged and non-waterlogged conditions in Sanjiang Plain, Northeast China. Results showed that the cumulative CO 2 emissions were significantly increased after leaf litter addition in both water conditions, and that the effect was more pronounced for DA amendment than CL regardless of water condition. The cumulative CO 2 efflux differed considerably between water conditions after DA addition, whereas no significant differences were found after CL addition. Remarkably impact of leaf litter types on cumulative CO 2 evolution was observed overall, water condition and interactions between leaf litter types and water conditions had no significant effect on CO 2 emissions, however. There were no non-additive effects of individual leaf litter type on total CO 2 efflux of the mixed-leaf litter addition treatments. The results of this study indicate that plant litter input to the C-rich marshy soil can induce rapid changes in SOC decomposition regardless of water conditions and that plant residue effects should be taken into consideration when assessing the dynamics of wetland soil system to the future climate scenarios. 相似文献
12.
Tropical peatlands are vital ecosystems that play an important role in global carbon storage and cycles. Current estimates of greenhouse gases from these peatlands are uncertain as emissions vary with environmental conditions. This study provides the first comprehensive analysis of managed and natural tropical peatland GHG fluxes: heterotrophic (i.e. soil respiration without roots), total CO 2 respiration rates, CH 4 and N 2O fluxes. The study documents studies that measure GHG fluxes from the soil ( n = 372) from various land uses, groundwater levels and environmental conditions. We found that total soil respiration was larger in managed peat ecosystems (median = 52.3 Mg CO 2 ha ?1 year ?1) than in natural forest (median = 35.9 Mg CO 2 ha ?1 year ?1). Groundwater level had a stronger effect on soil CO 2 emission than land use. Every 100 mm drop of groundwater level caused an increase of 5.1 and 3.7 Mg CO 2 ha ?1 year ?1 for plantation and cropping land use, respectively. Where groundwater is deep (≥0.5 m), heterotrophic respiration constituted 84% of the total emissions. N 2O emissions were significantly larger at deeper groundwater levels, where every drop in 100 mm of groundwater level resulted in an exponential emission increase (exp(0.7) kg N ha ?1 year ?1). Deeper groundwater levels induced high N 2O emissions, which constitute about 15% of total GHG emissions. CH 4 emissions were large where groundwater is shallow; however, they were substantially smaller than other GHG emissions. When compared to temperate and boreal peatland soils, tropical peatlands had, on average, double the CO 2 emissions. Surprisingly, the CO 2 emission rates in tropical peatlands were in the same magnitude as tropical mineral soils. This comprehensive analysis provides a great understanding of the GHG dynamics within tropical peat soils that can be used as a guide for policymakers to create suitable programmes to manage the sustainability of peatlands effectively. 相似文献
13.
Atmospheric concentrations of methane (CH 4) and nitrous oxide (N 2O) have increased over the last 150 years because of human activity. Soils are important sources and sinks of both potent greenhouse gases where their production and consumption are largely regulated by biological processes. Climate change could alter these processes thereby affecting both rate and direction of their exchange with the atmosphere. We examined how a rise in atmospheric CO 2 and temperature affected CH 4 and N 2O fluxes in a well‐drained upland soil (volumetric water content ranging between 6% and 23%) in a semiarid grassland during five growing seasons. We hypothesized that responses of CH 4 and N 2O fluxes to elevated CO 2 and warming would be driven primarily by treatment effects on soil moisture. Previously we showed that elevated CO 2 increased and warming decreased soil moisture in this grassland. We therefore expected that elevated CO 2 and warming would have opposing effects on CH 4 and N 2O fluxes. Methane was taken up throughout the growing season in all 5 years. A bell‐shaped relationship was observed with soil moisture with highest CH 4 uptake at intermediate soil moisture. Both N 2O emission and uptake occurred at our site with some years showing cumulative N 2O emission and other years showing cumulative N 2O uptake. Nitrous oxide exchange switched from net uptake to net emission with increasing soil moisture. In contrast to our hypothesis, both elevated CO 2 and warming reduced the sink of CH 4 and N 2O expressed in CO 2 equivalents (across 5 years by 7% and 11% for elevated CO 2 and warming respectively) suggesting that soil moisture changes were not solely responsible for this reduction. We conclude that in a future climate this semiarid grassland may become a smaller sink for atmospheric CH 4 and N 2O expressed in CO 2‐equivalents. 相似文献
14.
Understanding the responses of soil nitrous oxide (N 2O) emissions from terrestrial ecosystems to future CO 2 enrichment and warming is critical for the development of mitigation and adaptation policies. The effects of continuous increase in elevated CO 2 (EC) and elevated temperature (ET) on N 2O emissions are not fully known. We synthesized 209 measurements from 70 published studies and carried out a meta-analysis to examine individual and interactive effects of EC and ET on N 2O emissions from grasslands, croplands and forests. On average, a significant increase of 23% in N 2O emissions was observed under EC across all case studies. EC did not affect N 2O emissions from grasslands or forests, but significantly increased N 2O emissions in croplands by 38%. The extent of ET effects on N 2O emissions was nonsignificant and there was no significant difference in N 2O emission responses among these three terrestrial systems. ET only promoted N 2O emissions in forest by about 32% when ET was less than 2°C. The interactive effect of EC and ET on N 2O emissions was significantly synergistic, showing a greater increase than the sum of the effects caused by EC and ET alone. Our findings indicated that the combination of EC and ET substantially promoted soil N 2O and highlighted the urgent need to explore its mechanisms to better understand N 2O responses under future climate change. 相似文献
15.
The magnitude, temporal, and spatial patterns of soil‐atmospheric greenhouse gas (hereafter referred to as GHG) exchanges in forests near the Tropic of Cancer are still highly uncertain. To contribute towards an improvement of actual estimates, soil‐atmospheric CO 2, CH 4, and N 2O fluxes were measured in three successional subtropical forests at the Dinghushan Nature Reserve (hereafter referred to as DNR) in southern China. Soils in DNR forests behaved as N 2O sources and CH 4 sinks. Annual mean CO 2, N 2O, and CH 4 fluxes (mean±SD) were 7.7±4.6 Mg CO 2‐C ha ?1 yr ?1, 3.2±1.2 kg N 2O‐N ha ?1 yr ?1, and 3.4±0.9 kg CH 4‐C ha ?1 yr ?1, respectively. The climate was warm and wet from April through September 2003 (the hot‐humid season) and became cool and dry from October 2003 through March 2004 (the cool‐dry season). The seasonality of soil CO 2 emission coincided with the seasonal climate pattern, with high CO 2 emission rates in the hot‐humid season and low rates in the cool‐dry season. In contrast, seasonal patterns of CH 4 and N 2O fluxes were not clear, although higher CH 4 uptake rates were often observed in the cool‐dry season and higher N 2O emission rates were often observed in the hot‐humid season. GHG fluxes measured at these three sites showed a clear increasing trend with the progressive succession. If this trend is representative at the regional scale, CO 2 and N 2O emissions and CH 4 uptake in southern China may increase in the future in light of the projected change in forest age structure. Removal of surface litter reduced soil CO 2 effluxes by 17–44% in the three forests but had no significant effect on CH 4 absorption and N 2O emission rates. This suggests that microbial CH 4 uptake and N 2O production was mainly related to the mineral soil rather than in the surface litter layer. 相似文献
16.
Changes in soil hydration status affect microbial community dynamics and shape key biogeochemical processes. Evidence suggests that local anoxic conditions may persist and support anaerobic microbial activity in soil aggregates (or in similar hot spots) long after the bulk soil becomes aerated. To facilitate systematic studies of interactions among environmental factors with biogeochemical emissions of CO 2, N 2O and CH 4 from soil aggregates, we remolded silt soil aggregates to different sizes and incorporated carbon at different configurations (core, mixed, no addition). Assemblies of remolded soil aggregates of three sizes (18, 12, and 6 mm) and equal volumetric proportions were embedded in sand columns at four distinct layers. The water table level in each column varied periodically while obtaining measurements of soil GHG emissions for the different aggregate carbon configurations. Experimental results illustrate that methane production required prolonged inundation and highly anoxic conditions for inducing measurable fluxes. The onset of unsaturated conditions (lowering water table) resulted in a decrease in CH 4 emissions while temporarily increasing N 2O fluxes. Interestingly, N 2O fluxes were about 80% higher form aggregates with carbon placement in center (anoxic) core compared to mixed carbon within aggregates. The fluxes of CO 2 were comparable for both scenarios of carbon sources. These experimental results highlight the importance of hydration dynamics in activating different GHG production and affecting various transport mechanisms about 80% of total methane emissions during lowering water table level are attributed to physical storage (rather than production), whereas CO 2 emissions (~80%) are attributed to biological activity. A biophysical model for microbial activity within soil aggregates and profiles provides a means for results interpretation and prediction of trends within natural soils under a wide range of conditions. 相似文献
17.
Grazing ruminants urinate and deposit N onto pastoral soils at rates up to 1,000 kg ha ?1, with most of this deposited N present as urea. In urine patches, nitrous oxide (N 2O) emissions can increase markedly. Soil derived CO 2 fluxes can also increase due to priming effects.While N 2O fluxes are affected by temperature, no studies have examined the interaction of pasture plants, urine and temperature on N 2O fluxes and the associated CO 2 fluxes. We postulated the response of N 2O emissions to bovine urine application would be affected by plants and temperature. Dairy cattle urine was collected, labelled with 15N, and applied at 590 kg N ha ?1 to a sub-tropical soil,with and without pasture plants at 11°, 19°, and 23°C. Over the experimental period (28 days), 0.2% (11°C with plants) to 2.2% (23°C with plants) of the applied N was emitted as N 2O. At 11°C, plants had no effect on cumulative N 2O-N fluxes, whereas at 23°C, the presence of plants significantly increased the flux, suggesting plant-derived C supply affected the N 2O producing microbes. In contrast, a significant urine application effect on the cumulative CO 2 flux was not affected by varying temperature from 11?C23°C or by growing plants in the soil. This study has shown that plants and their responses to temperature affect N 2O emissions from ruminant urine deposition. The results have significant implications for forecasting and understanding the effect of elevated soil temperatures on N 2O emissions and CO 2 fluxes from grazed pasture systems. 相似文献
18.
Both soil and biochar properties are known to influence greenhouse gas emissions from biochar‐amended soils, but poor understanding of underlying mechanisms challenges prediction and modeling. Here, we examine the effect of six lignocellulosic biochars produced from the pyrolysis of corn stover and wood feedstocks on CO 2 and N 2O emissions from soils collected from two bioenergy cropping systems. Effects of biochar on total accumulated CO 2‐C emissions were minimal (<0.45 mg C g ?1 soil; <10% of biochar C), consistent with mineralization and hydrolysis of small labile organic and inorganic C fractions in the studied biochars. Comparisons of soil CO 2 emissions with emissions from microbially inoculated quartz–biochar mixtures (‘quartz controls’) provide evidence of soil and biochar‐specific negative priming. Five of six biochar amendments suppressed N 2O emissions from at least one soil, and the magnitude of N 2O emissions suppression varied with respect to both biochar and soil types. Biochar amendments consistently decreased final soil NO 3? concentrations, while contrasting effects on pH, NH 4+, and DOC highlighted the potential for formation of anaerobic microsites in biochar‐amended soils and consequential shifts in the soil redox environment. Thus, results implicated both reduced substrate availability and redox shifts as potential factors contributing to N 2O emission suppression. More research is needed to confirm these mechanisms, but overall our results suggest that soil biochar amendments commonly reduce N 2O emissions and have little effect on CO 2 emissions beyond the mineralization and/or hydrolysis of labile biochar C fractions. Considering the large C credit for the biochar C, we conclude that biochar amendments can reduce greenhouse gas emissions and enhance the climate change mitigation potential of bioenergy cropping systems. 相似文献
19.
To determine effects of soil fauna on greenhouse gas emissions, soil inoculated with different populations of nematodes and earthworms was incubated for 15 d. Soil with greater populations of nematodes and earthworms enhanced CO 2 and N 2O emissions. Cumulative emission fluxes of the two gases in the treatment of greater populations of nematodes and the treatment of greater populations of nematodes and earthworms were increased by 4.3 and 5.2 times for CO 2, 1.8 and 2.7 times for N 2O, respectively in comparison of the nematode-killed treatment. The emission fluxes of CO 2 and N 2O in soil treated with greater populations of nematodes were 19% for CO 2 and 21% for N 2O higher than those in soil treated with lower populations of nematodes. Meanwhile, the emission fluxes of the two gases in soil treated with greater populations of nematodes and earthworms were 12% for CO 2 and 27% for N 2O higher than those in soil treated with lower populations of nematodes and earthworms. The two gas fluxes were significantly correlated (R 2 = 0.9414; p < 0.001). Cumulative emissions of CO 2 and N 2O from soil treated with different populations of nematodes were positively correlated with DOC (dissolved organic carbon) concentration measured at the start of gas sampling (p < 0.05). 相似文献
20.
To determine effects of soil fauna on greenhouse gas emissions, soil inoculated with different populations of nematodes and earthworms was incubated for 15 d. Soil with greater populations of nematodes and earthworms enhanced CO 2 and N 2O emissions. Cumulative emission fluxes of the two gases in the treatment of greater populations of nematodes and the treatment of greater populations of nematodes and earthworms were increased by 4.3 and 5.2 times for CO 2, 1.8 and 2.7 times for N 2O, respectively in comparison of the nematode-killed treatment. The emission fluxes of CO 2 and N 2O in soil treated with greater populations of nematodes were 19% for CO 2 and 21% for N 2O higher than those in soil treated with lower populations of nematodes. Meanwhile, the emission fluxes of the two gases in soil treated with greater populations of nematodes and earthworms were 12% for CO 2 and 27% for N 2O higher than those in soil treated with lower populations of nematodes and earthworms. The two gas fluxes were significantly correlated (R 2 = 0.9414; p < 0.001). Cumulative emissions of CO 2 and N 2O from soil treated with different populations of nematodes were positively correlated with DOC (dissolved organic carbon) concentration measured at the start of gas sampling (p < 0.05). 相似文献
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