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1.
Yi Cheng Jing Wang Shen-Qiang Wang Jin-Bo Zhang Zu-Cong Cai 《Biology and Fertility of Soils》2014,50(7):1099-1108
Soil moisture changes, arising from seasonal variation or from global climate changes, could influence soil nitrogen (N) transformation rates and N availability in unfertilized subtropical forests. A 15?N dilution study was carried out to investigate the effects of soil moisture change (30–90 % water-holding capacity (WHC)) on potential gross N transformation rates and N2O and NO emissions in two contrasting (broad-leaved vs. coniferous) subtropical forest soils. Gross N mineralization rates were more sensitive to soil moisture change than gross NH4 + immobilization rates for both forest soils. Gross nitrification rates gradually increased with increasing soil moisture in both forest soils. Thus, enhanced N availability at higher soil moisture values was attributed to increasing gross N mineralization and nitrification rates over the immobilization rate. The natural N enrichment in humid subtropical forest soils may partially be due to fast N mineralization and nitrification under relatively higher soil moisture. In broad-leaved forest soil, the high N2O and NO emissions occurred at 30 % WHC, while the reverse was true in coniferous forest soil. Therefore, we propose that there are different mechanisms regulating N2O and NO emissions between broad-leaved and coniferous forest soils. In coniferous forest soil, nitrification may be the primary process responsible for N2O and NO emissions, while in broad-leaved forest soil, N2O and NO emissions may originate from the denitrification process. 相似文献
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Emissions of SO2 appear to have an acidifying effect on grossfall (open rainfall), throughfall, stemflow and soil solution at sites near major sources. Resulting effects on soil chemistry include elevated extractable acidity and aluminum and depressed exchangeable bases, especially Ca and Mg. These changes are mostly in the incipient phases in the study area. 相似文献
4.
Sami Ullah Rebeccah Frasier Leonora King Nathalie Picotte-Anderson Tim R. Moore 《Soil biology & biochemistry》2008,40(4):986-994
We conducted laboratory incubation experiments to elucidate the influence of forest type and topographic position on emission and/or consumption potentials of nitrous oxide (N2O) and methane (CH4) from soils of three forest types in Eastern Canada. Soil samples collected from deciduous, black spruce and white pine forests were incubated under a control, an NH4NO3 amendment and an elevated headspace CH4 concentration at 70% water-filled pore space (WFPS), except the poorly drained wetland soils which were incubated at 100% WFPS. Deciduous and boreal forest soils exhibited greater potential of N2O and CH4 fluxes than did white pine forest soils. Mineral N addition resulted in significant increases in N2O emissions from wetland forest soils compared to the unamended soils, whereas well-drained soils exhibited no significant increase in N2O emissions in-response to mineral N additions. Soils in deciduous, boreal and white pine forests consumed CH4 when incubated under an elevated headspace CH4 concentration, except the poorly drained soils in the deciduous forest, which emitted CH4. CH4 consumption rates in deciduous and boreal forest soils were twice the amount consumed by the white pine forest soils. The results suggest that an episodic increase in reactive N input in these forests is not likely to increase N2O emissions, except from the poorly drained wetland soils; however, long-term in situ N fertilization studies are required to validate the observed results. Moreover, wetland soils in the deciduous forest are net sources of CH4 unlike the well-drained soils, which are net sinks of atmospheric CH4. Because wetland soils can produce a substantial amount of CH4 and N2O, the contribution of these wetlands to the total trace gas fluxes need to be accounted for when modeling fluxes from forest soils in Eastern Canada. 相似文献
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Soil respiration and methane flux from adjacent forest, grassland, and cornfield were measured by using the closed chamber method from June to November, 1999 in Shizunai, Hokkaido, Japan, where the soil was an Aquic Humic Udivitrands derived from volcanic ash. The forest soil absorbed methane, at arate ranging from -0.12 to -0.02 mg C m-2 h-1, while the grassland soil emitted methane, at a rate ranging from undetectable levels to 0.18 mg C m-2 h-1. In the cornfield soil methane flux ranged from -0.01 to 0.04 mg C m-2 h-1. The soil respiration rate varied from 3 to 230 mg C m-2 h-1, 27 to 372 mg C m-2 h-1, and 29 to 156 mg C m-2 h-1 for the cornfield, grassland, and forest soils, respectively. Linear regression analysis demonstrated that the methane flux rate was positively correlated with the soil water-filled pore space (WFPS), and negatively correlated with the relative gas diffusion coefficient (D/D o) and air-filled pore space (AFPS). Soil respiration rates were positively correlated with the soil temperature at all the sites. The Q 10 value was 4.8, 3.3, and 1.9 for the cornfield, grassland, and forest soils, respectively. 相似文献
7.
Yang Xiong Zhu Yingmo Xu Yunjian Li Xiangnan Zhang Shuting Qian Qindong Wang Lingling Wu Jianping Chen Zhe 《Journal of Soils and Sediments》2022,22(10):2706-2719
Journal of Soils and Sediments - The montane subtropical forest soils contain huge nitrogen stocks, and climate warming might drive its volatilization due to the promotion of gaseous losses of... 相似文献
8.
T. Rütting D. Huygens P. Boeckx J. Staelens L. Klemedtsson 《Biology and Fertility of Soils》2013,49(6):715-721
Drained organic forest soils represent a hotspot for nitrous oxide (N2O) emissions, which are directly related to soil fertility, with generally higher emissions from N-rich soils. Highest N2O emissions have been observed in organic forest soils with low pH. The mechanisms for these high emissions are not fully understood. Therefore, the present study was conducted to gain a deeper insight into the underlying mechanisms that drive high N2O emissions from acid soils. Specifically, we investigated the microbial community structure, by phospholipid fatty acid analysis, along a natural pH gradient in an organic forest soil combined with measurements of physico-chemical soil properties. These were then statistically related to site-specific estimates of annual N2O emissions along the same natural pH gradient. Our results indicate that acidic locations with high N2O emissions had a microbial community with an increased fungal dominance. This finding points to the importance of fungi for N2O emissions from acid soils. This may either be directly via fungal N2O production or indirectly via the effect of fungi on the N2O production by other microorganisms (nitrifiers and denitrifiers). The latter may be due to fungal mediated N mineralization, providing substrate for N2O production, or by creating favourable conditions for the bacterial denitrifier community. Therefore, we conclude that enhanced N2O emission from acid forest soil is related, in addition to the known inhibitory effect of low pH on bacterial N2O reduction, to a soil microbial community with increased fungal dominance. Further studies are needed to reveal the exact mechanisms. 相似文献
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Nitrous oxide production by denitrification and nitrification in temperate forest, grassland and agricultural soils 总被引:2,自引:0,他引:2
P. AMBUS 《European Journal of Soil Science》1998,49(3):495-502
Nitrous oxide is produced in soils by biological denitrification and nitrification. To improve the fundamental understanding of the processes leading to N2O fluxes from soils, the production of N2O from denitrification and nitrification in spruce forest, beech forest, riparian grassland, coastal grassland and an agricultural field were studied. Samples were taken at a high and a low position along a topographic gradient in each site in the spring and autumn when the largest N2O fluxes were expected. They were incubated after being amended with N, and C2H2 was used as biological inhibitor to distinguish nitrification and denitrification. The N2O production in the low landscape position varied between 32 and 121 ng N cm?3 h?1 in the riparian grassland. 9 and 26 ng N cm?3 h?1 in the coastal grassland, and 135 and 195 ng N cm?3 h?1 in the agricultural field which was 10–100 times more than in the high positions where rates ranged between 3 and 5 ng N cm?3 h?1, 0.3 and 0.4 ng N cm?3 h?1, and 7 and 10 ng N cm?3 h?1, respectively. These differences almost certainly arose because the soil in the low positions was wetter and contained more organic matter. In the two forests N2O production was less than 1 ng N cm?3 h?1, strongly inhibited by O2, and not influenced by landscape position. Nitrification contributed to more than 60% of total N2O production in the riparian grassland. In the agricultural field nitrification produced 13–74% of the total N2O in the low position, and 10–88% in the high position. Denitrification was the dominant source of N2O in the coastal grassland except at the low position in the autumn where nitrification produced 60% of the total N2O. In the two forests where the soil had small nitrification potentials denitrification was the only source of N2O. In the other sites nitrification and denitrification potentials were large and of identical magnitude. The results emphasize the need to separate nitrification and denitrification at the process level and to recognize topography at the field scale when modelling N2O effluxes from soil. 相似文献
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Forest soils are commonly limited in nitrogen (N), and the removal of aboveground biomass in harvesting operations can exacerbate the problem. Thus, the soil organisms that facilitate the rate-limiting step in the N cycle, the oxidation of ammonium (NH4+), are of special interest in harvested environments. The objective of this study was to investigate the changes in ammonia oxidizing bacteria (AOB) communities that occurred in the years following clear cutting, and link those community shifts to availability of inorganic N forms NH4+ and nitrate (NO3?). Genetic fingerprinting targeting the amoA gene coupled with denaturing gel gradient electrophoresis was carried out over two summers on forest floor (LFH) and mineral (Ae) soils of three similar cutblocks harvested during different years. In-situ NH4+ and NO3? availability was measured over the growing seasons of 2009 and 2010, as well as a suite of physical soil characteristics. Results indicated that the AOB community composition differed in younger vs. older cutblocks, but not by soil horizon. The changes seen in the AOB paralleled the change in N bioavailability across sites, soil horizons, and sampling years, thus indicating that N bioavailability may be directly linked to AOB community composition. This link may provide the basis for the use of AOB as indicators of nutrient availability in the future. 相似文献
11.
Teodora Todorcic Vekic Shahid Nadeem Lars Molstad Vegard Martinsen Elisabeth Gautefall Hiis Lars Bakken Tobias Rütting Leif Klemedtsson Peter Dörsch 《Soil Use and Management》2023,39(3):1082-1095
Liming of acidic agricultural soils has been proposed as a strategy to mitigate nitrous oxide (N2O) emissions, as increased soil pH reduces the N2O/N2 product ratio of denitrification. The capacity of different calcareous (calcite and dolomite) and siliceous minerals to increase soil pH and reduce N2O emissions was assessed in a 2-year grassland field experiment. An associated pot experiment was conducted using homogenized field soils for controlling spatial soil variability. Nitrous oxide emissions were highly episodic with emission peaks in response to freezing–thawing and application of NPK fertilizer. Liming with dolomite caused a pH increase from 5.1 to 6.2 and reduced N2O emissions by 30% and 60% after application of NPK fertilizer and freezing–thawing events, respectively. Over the course of the 2-year field trial, N2O emissions were significantly lower in dolomite-limed than non-limed soil (p < .05), although this effect was variable over time. Unexpectedly, no significant reduction of N2O emission was found in the calcite treatment, despite the largest pH increase in all tested minerals. We tentatively attribute this to increased N2O production by overall increase in nitrogen turnover rates (both nitrification and denitrification) following rapid pH increase in the first year after liming. Siliceous materials showed little pH effect and had no significant effect on N2O emissions probably because of their lower buffering capacity and lower cation content. In the pot experiment using soils taken from the field plots 3 years after liming and exposing them to natural freezing–thawing, both calcite (p < .01) and dolomite (p < .05) significantly reduced cumulative N2O emission by 50% and 30%, respectively, relative to the non-limed control. These results demonstrate that the overall effect of liming is to reduce N2O emission, although high lime doses may lead to a transiently enhanced emission. 相似文献
12.
竹叶及其生物质炭输入对板栗林土壤N2O通量的影响 总被引:2,自引:1,他引:1
【目的】氧化亚氮(N2O)是温室气体的主要组成部分,其增温效应极强,陆地生态系统是N2O的主要排放源之一。人工林生态系统是陆地生态系统的重要组成部分,但目前关于经营措施对人工林生态系统土壤N2O通量的影响研究较少。本文研究了竹叶及其生物质炭输入对板栗林土壤N2O排放通量的影响,为调控亚热带人工林土壤N2O排放通量提供理论基础与科学依据。【方法】定位试验于2012年7月~2013年7月在浙江省临安市三口镇典型板栗林区进行,设对照、输入竹叶、输入生物质炭3个处理,利用静态箱-气相色谱法测定板栗林土壤N2O通量的动态变化以及土壤温度、土壤含水量、水溶性有机碳(WSOC)、水溶性有机氮(WSON)、微生物量碳(MBC)、微生物量氮(MBN)、NH+4-N和NO-3-N含量。【结果】不同处理条件下,板栗林土壤N2O排放通量均呈显著的季节性变化特征,最高值出现在7月,最低值出现在1月。与对照相比,竹叶处理的土壤N2O年平均通量和年累积排放量分别增加了17.2%和12.8%,而生物质炭处理的土壤N2O年平均通量和年累积排放量分别降低了27.4%和20.5%。竹叶处理的土壤WSON、MBN、NH+4-N及NO-3-N含量增加12.4%、19.1%、8.3%和13%,而生物质炭处理的NH+4-N和NO-3-N含量分别降低了14.1%和18%。在对照、竹叶以及生物质炭处理条件下,板栗林土壤N2O排放通量与土壤温度(表层5 cm处)和WSOC含量均有显著相关性(P 0.05),与土壤MBC含量均无显著相关性。竹叶处理土壤N2O通量与NH+4-N、NO-3-N及WSON含量均有显著相关性(P0.05)。【结论】在不同处理条件下,板栗林土壤N2O排放通量均呈现明显的季节性变化特征,表现为夏季高、 冬季低。输入竹叶可显著增加板栗林土壤N2O排放通量,而输入生物质炭N2O排放通量显著降低;输入竹叶和生物质炭可能是通过影响土壤碳库与氮库特征而影响土壤N2O的排放通量。 相似文献
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《Soil Science and Plant Nutrition》2013,59(6):812-818
Abstract To investigate the effects of renovation (ploughing and resowing) on nitrous oxide (N2O) emissions from grassland soil, we measured N2O fluxes from renovated and unrenovated (control) grassland plots. On 22 August in both 2005 and 2006 we harvested the sward, ploughed the surface soil and then mixed roots and stubble into the surface soil with a rotovator. Next, we compacted the soil surface with a land roller, spread fertilizer at 40 kg N ha?1 on the soil surface and sowed orchardgrass (Dactylis glomerata L., Natsumidori). In the control plot, we just harvested the sward and spread fertilizer. We determined N2O fluxes for 2 months after the renovation using a vented closed chamber. During the first 2 weeks, the renovated plot produced much more N2O than the control plot, suggesting that N was quickly mineralized from the incorporated roots and stubble. Even after 2 weeks, however, large N2O emissions from the renovated plot were recorded after rainfall, when the soil surface was warmed by sunshine and the soil temperature rose 2.7–3.0°C more than that of the control plot. In 2005, during the 67-day period from 19 August to 26 October, the renovated and control plots emitted 5.3 ± 1.4 and 2.8 ± 0.7 kg N2O-N ha?1, with maximum fluxes of 3,659 and 1,322 µg N2O-N m?2 h?1, respectively. In 2006, during the 65-day period from 21 August to 26 October, the renovated and control plots emitted 2.1 ± 0.6 and 0.96 ± 0.42 kg N2O-N ha?1, with maximum fluxes of 706 and 175 µg N2O-N m?2 h?1, respectively. The cumulative N2O emissions from plots in 2005 were greater than those in 2006, presumably because rainfall just after renovation was greater in 2005 than in 2006. These results suggest that incorporated roots and stubble may enlarge the anaerobic microsites in the soil in its decomposing process and increase the N2O production derived from the residues and the fertilizer. In addition, rainfall and soil moisture and temperature conditions during and after renovation may control the cumulative N2O emission. 相似文献
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Effects of soil texture and structure on carbon and nitrogen mineralization in grassland soils 总被引:6,自引:0,他引:6
J. Hassink 《Biology and Fertility of Soils》1992,14(2):126-134
Summary The hypotheses that disruption of soil structure increases mineralization rates in loams and clays more than in sandy soils and that this increase can be used to estimate the fraction of physically protected organic matter were tested. C and N mineralization was measured in undisturbed, and in finely and coarsely sieved moist or dried/remoistened soil. Fine sieving caused a temporary increase in mineralization. The relative increase in mineralization was much larger in loams and clays than in sandy soils and much larger for N than for C. The combination of remoistening and sieving of the soil gave a further increase in the mineralization flush after the disturbance. Again, the extra flush was larger in loams and clays than in sandy soils, and larger for N than for C. In loams and clays, small pores constituted a higher percentage of the total pore space than in sandy soils. The fraction of small pores explained more than 50% of the variation in the N mineralization rate between soils. There was also a good correlation between the small-pore fraction and the relative increase in N mineralization with fine sieving. For C, these relations were not clear. It is suggested that a large part of the organic matter that was present in the small pores could not be reached by microorganisms, and was therefore physically protected against decomposition. Fine sieving exposed part of this fraction to decomposition. This physically protected organic matter had a lower C: N ratio than the rest of the soil organic matter. The increase in N mineralization after fine sieving can be regarded as a measure of physically protected organic matter. 相似文献
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Organic C and N storage, and organic C fractions, in adjacent cultivated and forested soils of eastern Canada 总被引:1,自引:0,他引:1
M. R. Carter E. G. Gregorich D. A. Angers R. G. Donald M. A. Bolinder 《Soil & Tillage Research》1998,47(3-4):253-261
As a major attribute of soil quality, organic matter is responsive to agricultural land use practices including tillage. A study was initiated in eastern Canada to characterize changes in the masses of organic C and total N, and organic matter fractions in forested and adjacent cultivated or forage sites. Generally, the cultivated and forage sites had denser soil profiles than the forest sites. Based on an equivalent soil mass, to accommodate differences in soil bulk density, the paired forest and cultivated sites showed that cultivation decreased the mass of organic C (35%) and total N (10%) in the soil profile of the Podzolic soils, but increased organic C (25%) and total N (37%) in the Brunisolic (Cambisol) and Gleysolic soils. For the Podzolic soils, use of forages increased soil stored organic C and N by 55% and 35%, respectively. Organic C fractions were mainly of significance in the A horizon. Soil microbial biomass C was greater in the forested, compared to the cultivated soil, but the proportion of soil organic C as microbial biomass C (1.3% to 1.6%) was similar. The proportion, however, was greater (2.1%) for the forage soil, compared to the corresponding cultivated (1.3%) soil, suggesting that organic C was continuing to increase under the former. The relatively large proportion (19%) of organic C found in the light fraction of forest soils in the A horizon was decreased (up to 70%) by cultivation. In contrast, the proportion of macro-organic C present in the soil sand fraction was not greatly influenced by cultivation. Overall, soils in eastern Canada have a relatively large potential to store organic matter. The study illustrates the importance of soil type and cultivation interactions for maintenance of soil organic matter storage, and the positive influence of forages in this regard in agroecosystems. 相似文献
16.
Torsten Vor Jens Dyckmans Norman Loftfield Friedrich Beese Heiner Flessa 《植物养料与土壤学杂志》2003,166(1):39-45
The availability of O2 is one of the most important factors controlling the chemical and biological reactions in soils. In this study, the effects of different aeration conditions on the dynamics of the emission of trace gases (CO2, N2O, CH4) and the leachate composition (NO3‐, DOC, Mn, Fe) were determined. The experiment was conducted with naturally structured soil columns (silty clay, Vertisol) from a well aerated forest site. The soil monoliths were incubated in a microcosm system at different O2 concentrations (0, 0.001, 0.005, 0.01, 0.05, and 0.205 m3 m‐3 in the air flow through the headspace of the microcosms) for 85 days. Reduced O2 availability resulted in a decreased CO2 release but in increased N2O emission rates. The greatest cumulative N2O emissions (= 1.6 g N2O‐N m‐2) were observed at intermediate O2 concentrations (0.005 and 0.01 m3 m‐3) when both nitrification and denitrification occurred simultaneously in the soil. Cumulative N2O emissions were smallest (= 0.05 g N2O‐N m‐2) for the aeration with ambient air (O2 concentration: 0.205 m3 m‐3), although nitrate availability was greatest in this treatment. The emission of CH4 and leaching of Mn and Fe were restricted to the soil columns incubated under completely anoxic conditions. The sequence of the reduction processes under completely anoxic conditions complied with the thermodynamic theory: soil nitrate was reduced first, followed by the reduction of Mn(IV) and Fe(III) and finally CO2 was reduced to CH4. The re‐aeration of the soil columns after 85 days of anoxic incubation terminated the production of CH4 and dissolved Fe and Mn in the soil but strongly increased the emission rates of CO2 and N2O and the leaching of NO3‐ probably because of the accumulation of DOC and NH4+ during the previous anoxic period. 相似文献
17.
Purpose
The beneficial effect to the environment of nitrate (NO3 ?) removal by denitrification depends on the partitioning of its end products into nitrous oxide (N2O), nitric oxide (NO), and dinitrogen (N2). However, in subtropical China, acidic forest mineral soils are characterized by negligible denitrification capacity and thus reactive forms of N could not be effectively converted to inert N2, resulting in a negative environmental consequence. In this study, the influences of C input from litter decomposition on denitrification rate and its gaseous products under anoxic conditions in the acidic coniferous and broad-leaved forest soils in subtropical China were investigated using the acetylene (C2H2) blockage technique in the laboratory.Materials and methods
The coniferous and broad-leaved forest soils with and without litter addition were incubated under anaerobic conditions for 244 h. There were three treatments for each forest soil including addition of 0.5 and 1% corresponding litter (gram of litter per gram of soil) and the control without addition of litter.Results and discussion
The results showed that litter addition into the broad-leaved forest soil had no effect on average rates of denitrification (calculated as the sum of NO, N2O, and N2), whereas in the coniferous forest soil, the addition resulted in a significant increase in average denitrification rate. In the broad-leaved forest soil, both rates of litter addition decreased the production of NO but increased the production of N2, and high rates of litter addition into the coniferous forest soil promoted the reduction of N2O to N2.Conclusions
Increased decomposition of litter in the forest soils could effectively reduce N2O and NO production through denitrification under anaerobic conditions. 相似文献18.
Y. Xue H. M. van Es R. R. Schindelbeck B. N. Moebius‐Clune J. J. Melkonian C. Graham P. Yang 《Soil Use and Management》2013,29(2):240-249
Changes in the profile distribution of soil C stocks for conventional versus no‐tillage can affect N2O losses. Uncertainty remains whether deep N placement into a wetter layer in humid areas would affect N2O losses. This study evaluated the effects of soil carbon profile distribution (inverted, normal), depth of nitrogen placement (5 cm, 15 cm), temperature (10, 20 and 30 °C) and soil texture (clay loam, loamy sand) on N2O emissions from soil cores in a 216‐h incubation after simulated rainfall. N2O losses were larger from the clay loam than from the loamy sand, and cumulative N2O emissions from the inverted profile, with greater C levels at depth, were more than those from the profile with more C near the upper surface. Cumulative N2O losses from the inverted clay loam profile with deep N placement (1.16 mg N per kg dry soil; 0.71% of applied N) on average were almost double those in the loamy sand (0.62 mg N per kg dry soil; 0.42%). The smallest N2O losses were measured from the profiles with more C close to the upper surface with a shallow placement of N for the clay loam (0.19 mg N per kg dry soil; 0.12%) and loamy sand (0.33 mg N per kg dry soil; 0.23%). An exponential relationship between N2O fluxes and temperature was measured. We conclude that large N2O losses may occur under the combination of greater soil C content at deeper layers (ploughed soils) and moist profiles after N application (humid regions). Deep N placement appears to aggravate rather than ameliorate these concerns. 相似文献
19.
The formation of N2O as a result of denitrification was monitored under laboratory conditions in samples of a waterlogged Italian soil that had been amended with rice straw, KNO3 and (NH4)2HPO4. Redox potential and pH were also monitored. After four days of incubation N2O-N production reached a peak of 184.2 μg/d which declined to 29.05 μg/d on the seventh day. The production of N2O stabilized around this level for about 10 days and then declined to 1.57 μg/d, where it remained till the end of the experiment. 相似文献
20.
《Soil Science and Plant Nutrition》2013,59(6):806-811
Abstract To clarify the microbiological factors that explain high N2O emission in an arable peat soil in Central Kalimantan, Indonesia, a substrate-induced respiration-inhibition experiment was conducted for N2O production. The N2O emission rate decreased by 31% with the addition of streptomycin, whereas it decreased by 81% with the addition of cycloheximide, compared with a non-antibiotic-added control. This result revealed a greater contribution of the fungal community than bacterial community to the production of N2O in the soil. The population density of fungi in the soil, determined using the dilution plate method, was 5.5 log c.f.u. g?1 soil and 4.9 log c.f.u. g?1 soil in the non-selective medium (rose bengal) and the selective medium for Fusarium, respectively. The N2O-producing potential was randomly examined in each of these isolates by inoculation onto Czapek agar medium (pH 4.3) and incubation at 28°C for 14 days. Significant N2O-producing potential was found in six out of 19 strains and in five out of seven strains isolated from the non-selective and selective media, respectively. Twenty-three out of 26 strains produced more than 20% CO2 during the 14-day incubation period, suggesting the presence of facultative fungi in the soil. These strains were identified to be Fusarium oxysporum and Neocosmospora vasinfecta based on the sequence of 18S rDNA, irrespective of the N2O-producing potential and the growth potential in conditions of low O2 concentration. 相似文献