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1.
Laboratory incubations were conducted to study the effect of sodium chloride (NaCl) on denitrification and respiratory gases (CO2, O2) from soil treated with ammonium or nitrate and incubated at 20 % moisture. The same samples were assayed for denitrifying enzyme activity (DEA) after incubation at 40 % moisture with glucose and NO3–. Under aerobic conditions (20 % water content), a flush of activity was observed at 6 hours after start of incubation and subsided to negligible levels at 12 hours. Sodium chloride significantly depressed N2O and CO2 emissions and O2 consumption. Significantly more loss of N2O occurred from NH4+‐ than NO3–‐treated soil at all NaCl levels and was attributed to higher microbial activity. A highly significant positive correlation was obtained between N2O emission and respiratory gases. The respiratory quotient (CO2 evolved/O2) was higher for NH4+‐treated soil and decreased with the amount of NaCl. At 40 % moisture, N2O emissions were higher than at 20 % and peaked at 37 hours followed by a sharp decrease. Short‐term incubations of soil with NH4+ or NO3– did not have an effect on denitrifying enzyme activity (DEA) while NaCl had a positive effect, particularly in previously NO3–‐treated soil.  相似文献   

2.
Interactions between microbial communities and organic matter were analyzed for soils from the project regions ’︁Ecosystem Research in the Agricultural Landscape/FAM, Munich’ in southern Germany and ’︁Ecosystem Research in the Bornhöved Lake district’ from northern Germany using ratios between microbial biomass content (Cmic), microbial metabolic quotient (qCO2) and organic carbon content (Corg). In the agricultural soils in southern Germany, the qCO2/Corg ratio differed significantly with respect to agricultural management in contrast to ecophysiological Cmic/Corg ratio. In addition, Cmic/Corg ratio decreased from 39 to 21 mg Cmic g—1 Corg and qCO2/Corg ratio increased from 72 to 180 mg CO2‐C g—1 Cmic h—1 (g Corg g—1 soil)—1 with increasing soil depth. For the upper soil horizons from the landscape in northern Germany the two quotients differed significantly with reference to land use showing highest microbial colonization under grassland and lowest under beech forest. In contrast, C use efficiency was lowest in arable field under maize monoculture and highest in a wet grassland having a high organic C content.  相似文献   

3.
An incubation experiment was carried out to investigate the interactions of two straw qualities differing in N content and two soils differently accustomed to straw additions. One soil under conventional farming management (CFM) regularly received straw, the other soil under organic farming management (OFM) only farmyard manure. The soils of the two sites were similar in texture, pH, cation‐exchange capacity, and glucosamine content. The soil from the OFM site had higher contents of organic C, total N, muramic acid, microbial biomass C and N (Cmic and Nmic), but a lower ergosterol content and lower ratios ergosterol to Cmic and fungal C to bacterial C. The straw from the CFM had threefold higher contents of total N, twofold higher contents of ergosterol and glucosamine, a 50% higher content of muramic acid, and a 30% higher fungal C–to–bacterial C ratio. The straw amendments led to significant net increases in Cmic, Nmic, and ergosterol. Microbial biomass C showed on average a 50% higher net increase in the organic than in the CFM soil. In contrast, the net increases in Nmic and ergosterol differed only slightly between the two soils after straw amendment. The CO2 evolution from the CFM soil always exceeded that from the OFM, by 50% or 200 µg (g soil)–1 in the nonamended control soil and by 55% or additional 600 µg (g soil)–1 in the two straw treatments. In both soils, 180 µg g–1 less was evolved as CO2‐C from the OFM straw. The metabolic quotient qCO2 was nearly twice as high in the control and in the straw treatments of the CFM soil compared with that of the OFM. In contrast, the difference in qCO2 was insignificant between the two straw qualities. Differences in the fungal‐community structure may explain to a large extent the difference in the microbial use of straw in the two soils under different managements.  相似文献   

4.
控释氮肥养分控释效果及合理施用研究   总被引：19，自引：5，他引：19  
试验采用{3,3}单形重心设计方法,研究了普通尿素和2种包膜尿素D90、D60配比对土壤NH4+-N、NO3--N及矿质态氮(Nmin)含量的影响。结果表明,供试的7种包膜肥料初期溶出率均12.0%,微分溶出率在0.26%～2.49%之间。各处理土壤NH4+-N含量均随时间逐渐降低,而NO3--N和Nmin含量随时间逐渐增加。整个培养期内单独施用尿素处理,土壤NH4+-N、NO3--N及Nmin含量最高;2种控释肥单施或其配比施用土壤NH4+-N、NO3--N及Nmin含量最低;尿素与控释肥配合施用,土壤NH4+-N、NO3--N及Nmin含量居中。不同时期内土壤NH4+-N的来源不同,0～20d内,尿素对土壤NH4-N含量贡献最大;30～50d内,土壤NH4+-N主要来自D60;整个培养期内尿素对土壤NO3--N和Nmin的贡献均最大。肥料配比中随着尿素比例的减少,土壤NH4+-N、NO3--N及Nmin均逐渐减少。研究结果初步验证了混料设计在肥料配比研究中的可行性。  相似文献   

5.
 A study of the effects of different qualities (fresh and composted) and rates (equivalent to 120, 240, and 360 kg N ha–1) of mustard meal application on wheat yields on humid tropical vertisol was started in 1990 at Ginchi Research Station in Ethiopia. After continuous wheat cropping for 7 years and without any further fertilisation, soil microbial parameters (basal respiration, microbial biomass-C and N, organic-C, and ecophysiological quotients) were studied during one growth period. After 7 years of application, mustard meal still exerted a significant positive effect on microbial biomass, basal respiration, organic-C, Cmic : Nmic ratio, and metabolic quotient (qCO2). Organic-C, qCO2 and Cmic : Nmic ratios were higher for the compost-amended plots than plots amended with fresh mustard meal. Basal respiration, Cmic, and Cmic : Nmic ratio showed a clear seasonality, but only in manured plots. The data indicate shifts in microbial community structure (from bacteria to fungi and from r to K strategists) and suggest positive medium-term effects of mustard meal on humid tropical vertisol biological qualities. Received: 25 May 1999  相似文献   

6.
Soil samples from the upper 10-cm-thick layer of the humus horizon (without forest litter) were taken in Podol’sk and Serpukhov districts (1130 and 1080 km2, respectively) of Moscow oblast. At each sampling site, ecosystem (forest, plowland, or fallow), soil (soddy-podzolic, soddy-gley, bog-podzolic, meadow alluvial, gray forest, and anthropogenically transformed soils of lawns and industrial zones), predominant vegetation, and topography (floodplain and low, medium, and upper parts of watersheds) were determined. The carbon content of the microbial biomass (Cmic) was determined by the method of substrate-induced respiration; we also determined the rate of basal (microbial) respiration (BR) and the organic carbon content, pH, and particle-size distribution. Overall, 237 samples from Serpukhov district and 45 samples from Podol’sk district were analyzed. The BR/Cmic ratios (respiration quotient qCO2) and Cmic/Corg ratios were calculated. The Cmic content in the soils ranged from 43 to 1394 μg C/kg; the BR varied from 0.06 to 25 μg CO2-C/g per h, qCO2, from 0.34 to 6.52 μg CO2-C/mg Cmic per h; and the Cmic/Corg ratio, from 0.19 to 10.65%. It was found that the most significant factors affecting the variability of the Cmic and BR are the parameters of ecosystem (50% and 80%, respectively) and soil (30% and 9%, respectively). The most significant variability of these indices was found in forest soils; it was mainly controlled by the soil texture (33 and 23%) and the Corg content (19 and 24%). The Cmic parameter made it possible to differentiate the soils of the territory for the purposes of their evaluation, monitoring, and biological assessment more clearly than the BR value and the soil chemical characteristics.  相似文献   

7.
Microbial biomass, respiratory activity, and in‐situ substrate decomposition were studied in soils from humid temperate forest ecosystems in SW Germany. The sites cover a wide range of abiotic soil and climatic properties. Microbial biomass and respiration were related to both soil dry mass in individual horizons and to the soil volume in the top 25 cm. Soil microbial properties covered the following ranges: soil microbial biomass: 20 µg C g–1–8.3 mg C g–1 and 14–249 g C m–2, respectively; microbial C–to–total organic C ratio: 0.1%–3.6%; soil respiration: 109–963 mg CO2‐C m–2 h–1; metabolic quotient (qCO2): 1.4–14.7 mg C (g Cmic)–1 h–1; daily in‐situ substrate decomposition rate: 0.17%–2.3%. The main abiotic properties affecting concentrations of microbial biomass differed between forest‐floor/organic horizons and mineral horizons. Whereas microbial biomass decreased with increasing soil moisture and altitude in the forest‐floor/organic horizons, it increased with increasing Ntot content and pH value in the mineral horizons. Quantities of microbial biomass in forest soils appear to be mainly controlled by the quality of the soil organic matter (SOM), i.e., by its C : N ratio, the quantity of Ntot, the soil pH, and also showed an optimum relationship with increasing soil moisture conditions. The ratio of Cmic to Corg was a good indicator of SOM quality. The quality of the SOM (C : N ratio) and soil pH appear to be crucial for the incorporation of C into microbial tissue. The data and functional relations between microbial and abiotic variables from this study provide the basis for a valuation scheme for the function of soils to serve as a habitat for microorganisms.  相似文献   

8.
The turnover of organic matter determines the availability of plant nutrients in unfertilized soils, and this applies particularly to the alkaline saline soil of the former Lake Texcoco in Mexico. We investigated the effects of alkalinity and salinity on dynamics of organic material and inorganic N added to the soil. Glucose labelled with 14C was added to soil of the former Lake Texcoco drained for different lengths of time, and dynamics of 14C, C and N were investigated with the Detran model. Soil was sampled from an undrained plot and from three drained for 1, 5 and 8 years, amended with 1000 mg 14C‐labelled glucose kg?1 and 200 mg NH4+‐N kg?1, and incubated aerobically. Production of 14CO2 and CO2, dynamics of NH4+, NO2– and NO3–, and microbial biomass 14C, C and N were monitored and simulated with the Detran model. A third stable microbial biomass fraction had to be introduced in the model to simulate the dynamics of glucose, because > 90 mg 14C kg?1 soil persisted in the soil microbial biomass after 97 days. The observed priming effect was mostly due to an increased decay of soil organic matter, but an increased turnover of the microbial biomass C contributed somewhat to the phenomenon. The dynamics of NH4+ and NO3– in the NH4+‐amended soil could not be simulated unless an immobilization of NH4+ into the microbial biomass occurred in the first day of the incubation without an immediate incorporation of it into microbial organic material. The dynamics of C and a priming effect could be simulated satisfactorily, but the model had to be adjusted to simulate the dynamics of N when NH4+ was added to alkaline saline soils.  相似文献   

9.
Burning of the vegetation in the African savannahs in the dry season is widespread and may have significant effects on soil chemical and biological properties. A field experiment in a full factorial randomised block design with fire, ash and extra grass biomass as main factors was carried out in savannah woodland of the Gambella region in Ethiopia. The microbial biomass C (Cmic) was 52% (fumigation-extraction) and 20% (substrate-induced respiration) higher in burned than unburned plots 12 d after burning. Both basal respiration and potential denitrification enzyme activity (PDA) immediately responded to burning and increased after treatment. However, in burned plots addition of extra biomass (fuel load) led to a reduction of Cmic and PDA due to enhanced fire temperature. Five days after burning, there was a short-lived burst in the in situ soil respiration following rainfall, with twice as high soil respiration in burned than unburned plots. In contrast, 12 d after burning soil respiration was 21% lower in the burned plots, coinciding with lower soil water content in the same plots. The fire treatment resulted in higher concentrations of dissolved organic C (24-85%) and nitrate (47-76%) in the soil until 90 d after burning, while soil NH4+-N was not affected to the same extent. The increase in soil NO3−-N but not NH4+-N in the burned plots together with the well-aerated soil conditions indicated that nitrifying bacteria were stimulated by fire and immediately oxidised NH4+-N to NO3−-N. In the subsequent rainy season, NO3−-N and, consequently, PDA were reduced by ash deposition. Further, Cmic was lower in burned plots at that time. However, the fire-induced changes in microbial biomass and activity were relatively small compared to the substantial seasonal variation, suggesting transient effects of the low severity experimental fire on soil microbial functioning.  相似文献   

10.
《Applied soil ecology》2007,35(3):660-669
The current study tested the contribution of native Acacia species of the Sudano-Sahelian zone to improving organic carbon and nitrogen level in Cambisols and Vertisols with specific focus on variation in microbial biomass (Cmic), soil basal respiration (Cresp) and metabolic quotient (qCO2). The results show enrichment in total organic carbon (Ctotal), in total nitrogen (Ntotal) and higher clay content under Acacia canopies as compared to adjacent open grasslands. The relative nutrient concentration in Acacia cover showed an increase in Cmic ranging from 203 to 572 μg g−1 whereas in adjacent open grassland it varied from 100 to 254 CO2–C μg g−1. As a function of Cmic (r = 0.60), Ctotal (r = 0.70) and Ntotal (r = 0.70), Cresp was higher under Acacia canopies than open grassland and this difference was more pronounced when measured over lengthier incubation periods (10–21 days). A lower qCO2 under Acacia cover (except for one site) demonstrated a change in microorganisms communities structure and higher substrate use efficiency as compared to open grassland. The results also show that soil texture, as well as vegetation cover, influenced microbial processes. The negative correlation between clay content and carbon mineralization (Cresp/Ctotal, qCO2), and positive linear relation between clay and Cmic supported the hypothesis that finer soil texture protects soil microbial biomass against degradation and limits organic matter mineralization. The specific effects of soil typology and vegetation cover on Cmic and qCO2 variability were significant, but the greater effects were attributed to vegetation cover.  相似文献   

11.
Liming or vermicomposting eliminates pathogens from wastewater sludge, but might affect CO2 and N2O emissions when added to soil. Soil incubated at 40%, 60%, 80% and 100% of its water holding capacity (WHC) was amended with limed or unlimed wastewater sludge, vermicompost or inorganic fertilizer, while emissions of N2O and CO2 and mineral N concentrations were monitored in aerobic incubation experiment for 7 days. Application of unlimed wastewater sludge significantly increased the emission of CO2 compared to the unamended soil, but not the other treatments except when unlimed wastewater sludge was added to soil incubated at 60% WHC. The emission of CO2, was generally largest in soil incubated at 60% WHC and lowest in soil incubated at 100% WHC. The emission of N2O after 1 day was significantly larger in soil amended with unlimed wastewater sludge compared to the other treatments, but not when soil was incubated at 100% WHC. The emission of N2O increased with increased soil water content. The concentration of NH4+ was largest in soil amended with limed or unlimed wastewater sludge and lowest in the unamended soil and soil water content had no clear effect on it. In soil incubated at 40%, 60% and 80% WHC, the largest amount of NO3− was found in soil amended with inorganic fertilizer and vermicompost and the lowest in the soil amended with unlimed wastewater sludge. The concentration of NO3− in soil decreased when the soil water content increased in all treatments, except in the soil amended with unlimed wastewater sludge. It was found that water content affected the emission of CO2 of N2O and the concentration of NO3−, but not the amount of NH4+ and NO2− in soil. Application of unlimed wastewater sludge increased the emissions of CO2 and N2O and the concentrations of NH4+, but decreased the amount of NO3− in soil.  相似文献   

12.
In 11 rain‐fed arable soils of the Potohar plateau, Pakistan, the amounts of microbial‐biomass C (Cmic), biomass N (Nmic), and biomass P (Pmic) were analyzed in relation to the element‐specific total storage compartment, i.e., soil Corg, Nt, and Pt. The effects of climatic conditions and soil physico‐chemical properties on these relationships were highlighted with special respect to crop yield levels. Average contents of soil Corg, Nt, and Pt were 3.9, 0.32, and 0.61 mg (g soil)–1, respectively. Less than 1% of Pt was extractable with 0.5 M NaHCO3. Mean contents of Cmic, Nmic, and Pmic were 118.4, 12.0, and 3.9 µg (g soil)–1. Values of Cmic, Nmic, Pmic, soil Corg, and Nt were all highly significantly interrelated. The mean crop yield level was closely connected with all soil organic matter– and microbial biomass–related properties, but showed also some influence by the amount of precipitation from September to June. Also the fraction of NaHCO3‐extractable P was closely related to soil organic matter, soil microbial biomass, and crop yield level. This reveals the overwhelming importance of biological processes for P turnover in alkaline soils.  相似文献   

13.
The response of terrestrial ecosystems to elevated atmospheric CO2 is related to the availability of other nutrients and in particular to nitrogen (N). Here we present results on soil N transformation dynamics from a N-limited temperate grassland that had been under Free Air CO2 Enrichment (FACE) for six years. A 15N labelling laboratory study (i.e. in absence of plant N uptake) was carried out to identify the effect of elevated CO2 on gross soil N transformations. The simultaneous gross N transformation rates in the soil were analyzed with a 15N tracing model which considered mineralization of two soil organic matter (SOM) pools, included nitrification from NH4+ and from organic-N to NO3− and analysed the rate of dissimilatory NO3− reduction to NH4+ (DNRA). Results indicate that the mineralization of labile organic-N became more important under elevated CO2. At the same time the gross rate of NH4+ immobilization increased by 20%, while NH4+ oxidation to NO3− was reduced by 25% under elevated CO2. The NO3− dynamics under elevated CO2 were characterized by a 52% increase in NO3− immobilization and a 141% increase in the DNRA rate, while NO3− production via heterotrophic nitrification was reduced to almost zero. The increased turnover of the NH4+ pool, combined with the increased DNRA rate provided an indication that the available N in the grassland soil may gradually shift towards NH4+ under elevated CO2. The advantage of such a shift is that NH4+ is less prone to N losses, which may increase the N retention and N use efficiency in the grassland ecosystem under elevated CO2.  相似文献   

14.
Short-term metabolic activities, including ammonincation, nitrification, denitrification and the release of CO2, with and without added substrate, and most probable numbers of ammonifiers, nitrifiers and denitrifiers were measured on stored topsoil from pasture over 140 days in the absence of growing plants. Parallel samples of irradiated and untreated soil were examined. Release of mineral-N, chiefly as NH+4N, was greater from the irradiated soil. In the untreated soil there was a slight increase in NO3?N. Microorganisms (estimated by MPN method) and microbial respiration in the untreated soil increased, and then diminished with time.The release of 13N2O and 13N2 was measured from intact soil cores amended with 13NO3?N and 13NH+4N. The principal product from the treated soil when 13NO3?N was added was 13N2, with little 13N2O, whereas the irradiated soil evolved both 13N2 and 13N2O. Similarly, the irradiated soil continuously evolved 13N2O from 13NH+4N in contrast to the untreated soil.  相似文献   

15.
Summary Studies of the effects of different forms of N on urease production in soils amended with organic C showed that although microbial activity, as measured by CO2 production, was stimulated by the addition of NH4 + or NO3 - to C-amended soils (200 mol glucose-C g–1 soil), urease production was repressed by these forms of N. The addition of L-methionine sulfoximine, an inhibitor of inorganic N assimilation by microorganisms, relieved the NH4 + and NO3 - repression of urease production in C-amended soil. The addition of sodium chlorate, an inhibitor of NO3 - reduction to NH4 + by microorganisms, relieved the NO3 - repression of urease production, but did not eliminate the repression associated with NH4 +. These observations indicate that microbial production of urease in C-amended soils is not directly repressed by NH4 + or NO3 -, but by products formed by microbial assimilation of these forms of N. This conclusion is supported by our finding that the biologically active L-isomers of alanine, arginine, asparagine, aspartate, and glutamine, repressed urease production in C-amended soil, whereas the D-isomers of these amino acids had little or no influence on urease production. This work suggests that urease synthesis by soil microorganisms is controlled by the global N regulon.  相似文献   

16.
In the mineral horizons of the soils under different southern taiga forests (oak, archangel spruce, and aspen in the Kaluzhskie Zaseki Reserve of Kaluga region and the green moss spruce and spruce-broadleaved forests of the Zvenigorod Biological Station of Moscow State University in Moscow region), the carbon content in the microbial biomass (Cmic), the rate of the basal respiration (BR), and the specific microbial respiration (qCO2= BR/Cmic) were determined. The Cmic content was measured using the method of substrate-induced respiration (SIR). In the upper humus horizons of the soils, the Cmic content amounted to 762–2545 μg/g and the BR ranged from 1.59 to 7.55 μg CO2-C/g per h. The values of these parameters essentially decreased down the soil profiles. The portion of Cmic in the organic carbon of the humus horizons of the forest soils was 4.4 to 13.2%. The qCO2values increased with the depth in the soils of the Biological Station and did not change in the soils of the Reserve. The pool of Cmic and Corg and the microbial production of CO2 (BR) within the forest soil profiles are presented.  相似文献   

17.
In a forest in Flanders (Belgium), situated in a region of intensive livestock production, comparable stands of Corsican pine and silver birch were studied for (1) NH4 + and NO3 - concentrations in throughfall water and soil solution and (2) depositions and leaching of NH4 + and NO3 - to groundwater. In each stand, throughfall collectors and porous cup lysimeters at three depths (0.1m, 0.5m and 1m) were installed in three replicated sets. Throughfall concentrations of ammonium and nitrate were significantly different for both species as well as soil solution concentrations of nitrate at all depths. Under pine, nitrate concentrations of the soil solution at 1m depth clearly exceeded the Belgian critical level for drinking water (50 mg.1-1). Under birch, this level was only sporadically exceeded. During the sampling period, the depositions of NH4 +-N and NO3 --N reached respectively 21.6 kg/ha and 6.3 kg/ha under birch and 81.3 and 15.2 kg/ha under Corsican pine. Nitrate-N leaching under silver birch amounted 25.4 kg/ha whereas 56.4 kg/ha was measured under Corsican pine.  相似文献   

18.
《Applied soil ecology》2010,46(3):225-231
There are plans to vegetate soil of the former lake Texcoco and use wastewater sludge to provide nutrients. However, the Texcoco soil is N depleted, so the amount of N available to the vegetation might be limited and the dynamics of C and N affected. We investigated how emissions of CO2, N2O and N2, and dynamics of mineral N were affected when different types of N fertilizer, i.e. NH4+, NO3−, or unsterilized or sterilized wastewater sludge, were added to the Texcoco soil. An agricultural soil served as control. Sewage sludge added to an alkaline saline soil (Texcoco soil) induced a decrease in concentrations of NH4+ and NO3−. Addition of sewage sludge increased the CO2 emission rate > two times compared to soil amended with sterilized sludge. The NH4+ concentration was lower when sludge was added to an agricultural soil for the first 28 days and in the Texcoco soil for 56 days compared to soil amended with sterilized sludge. Production of N2O in the agricultural soil was mainly due to nitrification, even when sludge was added, but denitrification was the main source of N2O in the Texcoco soil. Microorganisms in the sludge reduced N2O to N2, but not the soil microorganisms. It was found that microorganisms added with the sludge accelerated organic material decomposition, increased NH4+ immobilization, and induced immobilization of NO3− (in Texcoco soil). These results suggest that wastewater sludge improves soil fertility at Otumba (an agricultural soil) and would favour the vegetation of the Texcoco soil (alkaline saline).  相似文献   

19.
Sandy loam soil, with added glucose, was incubated anaerobically under N2 and subjected to repeated 1-h C2H2 reduction assays. In the presence of 1% glucose the addition of 50 μg NH4+ ?N/g or of 20 μg NO?3 N/g (untreated soil contained 1.2 μg NH+4?N and 7.10 μg NO?3-N/g) caused at least some suppression of nitrogenase activity. Activity developed when the KCl-extractable soil inorganic nitrogen concentration dropped below 35 μg/g. In the presence of 0.1 or 0.05% glucose the addition of 5 μg NH+4?N/g caused some suppression of nitrogenase activity. However, activity developed when the soil NH4+-N concentration dropped below about 4 μg/g. With 0.1% glucose and 5 μg added NO?2 N/g, activity did not develop until the soil NO?2 -N concentration dropped to zero. Added NO?3 N was rapidly reduced and denitrified to NO?2- N, N2O-N and NH+4 N and furthermore caused some inhibition of CO2 evolution. The data from NH4?-addition experiments are consistent with a nitrogenase repression/ derepression threshold of 4 and 35μg NH+4-N/g at 0.05 and 1% glucose concentrations, respectively. The data from NO?2- and NO?3-addition experiments suggest a combination of repression and toxicity effects in the presence of added NO?3 N.  相似文献   

20.
Marine ecosystems are a known net source of greenhouse gases emissions but the atmospheric gas fluxes, particularly from the mangrove swamps occupying inter-tidal zones, are characterized poorly. Spatial and seasonal fluxes of nitrous oxide (N2O) and carbon dioxide (CO2) from soil in Mai Po mangrove swamp in Hong Kong, South China and their relationships with soil characteristics were investigated. The N2O fluxes averaged from 32.1 to 533.7 μg m−2 h−1 and the CO2 fluxes were between 10.6 and 1374.1 mg m−2 h−1. Both N2O and CO2 fluxes in this swamp showed large spatial and seasonal variations. The fluxes were higher at the landward site than the foreshore bare mudflat, and higher fluxes were recorded in warm, rather than cold, seasons. The landward site had the highest content of soil organic carbon (OC), total Kjeldahl nitrogen (TKN), nitrate (NO3−–N) and total phosphorus (TP), while the bare mudflat had the highest ammonium nitrogen (NH4+–N) concentration and soil denitrification potential activity. The N2O flux was related, positively, to CO2 flux. Soil NO3−–N and TP increased N2O flux, while soil OC and TP concentrations contributed to the CO2 flux. The results indicated that the Mai Po mangrove swamp emitted significant amounts of greenhouse gases, and the N2O emission was probably due to soil denitrifcation.  相似文献   

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