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1.
土壤含水量与N2O产生途径研究   总被引:47,自引:5,他引:42  
土壤含水量变化对N2O产生和排放影响的研究表明,不同含水量情况下,N2O排放也不相同.特别是用乙炔抑制技术证明了在播种前后,气候干燥而土壤含水量较低的情况下,N2O产生主要来自于硝化过程;降雨后,土壤含水量较高时,N2O主要是通过反硝化过程产生;而在农田中等含水量情况下,土壤微生物的硝化和反硝化作用产生的N2O大约各占一半.指出旱作农田N2O产生途径主要取决于土壤水分的控制和调节.  相似文献   

2.
土壤中反硝化酶活性变化与N2O排放的关系   总被引:15,自引:0,他引:15  
研究施肥条件下,土壤反硝化酶活性硝酸还原酶(NR)活性、亚硝酸还原酶(NiR)活性及羟胺还原酶(HyR)活性在玉米生长季节中的变化及其与土壤含水量、硝态氮含量、N2O排放之间的关系.结果表明,3种还原酶都有明显的季节变化规律并受土壤水分含量及施肥的影响.通过研究3种反硝化酶活性与土壤含水量及N2O排放量之间的关系后指出,反硝化酶活性变化可作为一个区分旱田N2O产生途径的指标  相似文献   

3.
根际优势菌耐药菌株的获得及其^1^5N标记   总被引:4,自引:0,他引:4       下载免费PDF全文
对两株具有反硝化活性的根际优势细菌进行了耐药性和 ̄(15)N标记;研究了该双标记菌株在土壤中的动态及其活性。结果表明,所用双标记方法是可行的,应用标记菌株可以追踪其在土壤中的消长。结果还表明,标记 ̄(15)N菌株的 ̄(15)N丰度与供试培养基中氮源的 ̄(15)N丰度相近;标记菌株的反硝化活性与出发菌株的相同。  相似文献   

4.
设施栽培下土壤中硝化、反硝化作用的研究   总被引:10,自引:0,他引:10  
殷永娴  刘鸿雁 《生态学报》1996,16(3):246-250
利用温室、大棚等园艺设施栽种蔬菜,是当今蔬菜生产的有效措施之一,但由于温室,大棚是一个特殊的环境,加上连作,致使温度室、大棚的土壤逐渐产生障碍,导致作物产量逐渐下降,本文着重从温室、大棚土壤中硝化、反硝化作用进行深入一步探讨,其结果为:温室、大棚中有强烈的硝化作用和较多的NO2^-、NO3^-盐积累,这是温室、大棚作物产量下降的重要原因之一;温室,大棚中反硝化作用强度与土壤中的NO3^-盐含量有关  相似文献   

5.
通过水稻盆栽试验,分别于水稻分蘖期和孕穗期采集根际与非根际土壤,利用末端限制性片段长度多态技术(T-RFLP)和实时荧光定量PCR(qPCR)技术探究水稻生长对根际反硝化作用和反硝化微生物的影响.结果表明: 分蘖期根际土壤的反硝化势显著低于非根际土壤,而孕穗期根际与非根际土壤的反硝化势没有显著性差异.但分蘖期和孕穗期根际土壤中含narGnosZ基因的微生物数量均显著高于非根际土壤,其中含nosZ基因的反硝化微生物的群落组成结构和多样性对根际环境响应更敏感.说明虽然水稻根系生长会刺激反硝化微生物的生长繁殖,但抑制了根际土壤中一些反硝化微生物的活性,从而降低了根际土壤的反硝化潜势.  相似文献   

6.
一氧化氮(NO)在氮的生物地球化学循环、大气环境化学和全球变暖中起着重要作用。森林土壤是NO的一个重要来源。硝化、反硝化、硝化细菌反硝化以及化学反硝化是森林土壤NO产生的主要途径。当前,关于各个过程对NO排放的相对贡献以及生物和环境因子对各个过程NO产生的影响还缺乏系统性研究。因而,本文旨在综述森林土壤NO产生的主要途径,各途径来源NO的测定方法以及土壤氮循环功能基因和环境因子对不同来源土壤NO排放的影响,并在此基础上指出了研究的薄弱环节与未来研究方向。总体而言,森林土壤NO的排放主要来自硝化和反硝化作用,但是在酸性土壤中不能忽视化学反硝化过程对其排放的影响。在量化各个过程对土壤NO排放贡献时,15N-18O双同位素富集法比传统的硝化抑制剂法能更准确地区分NO的来源。土壤NO的产生是各种生物和非生物过程综合作用的结果,当前有关氮循环功能基因丰度与土壤NO排放关系的研究中,缺乏将氮循环功能基因和土壤各过程产生的NO排放联系起来研究。在探究环境因子对土壤NO排放影响时,更多关注单个环境因子对土壤硝化和反硝化过程来源NO排放的影响,而对硝化细菌反硝化和化学反硝化过程来源NO排放的研究较少,而且也缺乏多个环境因子共同作用对不同过程NO排放影响的研究。  相似文献   

7.
丹麦森林土壤反硝化作用的动力学分析   总被引:2,自引:0,他引:2  
本项研究将乙炔和氯霉素抑制技术结合起来 ,对丹麦一森林土壤的反硝化作用进行了研究 ,并考察温度对其还原酶活性的影响 .反硝化还原酶活性和合成过程受O2 的抑制 ,厌氧培养时 ,需要一定时间消耗系统中残余的O2 来解除这种抑制作用 .在无抗生素抑制蛋白质合成时 ,硝酸还原酶只有少量合成 ,而N2 O还原酶却显著地诱导产生 .这一结果对土壤吸收N2 O能力的研究具有重要意义 .在各处理下 ,系统中未发生亚硝酸盐的明显积累 ,表明亚硝酸还原酶活性大于硝酸还原酶 .外加葡萄糖加速了反硝化作用 ,并能促进酶的合成和消除还原过程中的电子竞争 .供试土壤表现出很强的厌氧呼吸作用 ,并受外加C源的促进 .反硝化作用的活化能低于土壤厌氧呼吸的活化能 ,因此反硝化作用的Q1 0值较低 ,CO2 和N2 O的产生比例随温度升高而加大 .  相似文献   

8.
对两株具有反硝化活性的根际优势细菌进行了耐药性和15N标记;研究了该双标记菌株在土壤中的动态及其活性。结果表明,所用双标记方法是可行的,应用标记菌株可以追踪其在土壤中的消长。结果还表明,标记15N菌株的15N丰度与供试培养基中氮源的15N丰度相近;标记菌株的反硝化活性与出发菌株的相同。  相似文献   

9.
玉米植株对大田温室气体N2O排放的影响   总被引:9,自引:0,他引:9  
利用封闭式箱法对玉米田N2O排放通量的观测表明,大田种植玉米后,对N2O排放产生了很大影响,玉米土壤系统的N2O排放通量大于不种玉米的土壤.此外,植物根系能明显促进土壤中N2O的排放,特别是在玉米生长后期尤为明显.从播种开始到年底,施尿素导致N2O排放为3.3kg·hm-2,玉米植株为0.69kg·hm-2,占总排放量的17.3%.  相似文献   

10.
氢醌和双氰胺对种稻土壤N2O和CH4排放的影响   总被引:14,自引:1,他引:13  
通过盆栽试验,研究了脲酶抑制剂氢醌(HQ)、硝化抑制剂双氰胺(DCD)及二者的组合(HQ+DCD)对种稻土壤N2O和CH4排放的影响.结果表明,在未施麦秸粉时,所有施抑制剂的处理均较单施尿素的能显著减少水稻生长期供试土壤N2O和CH4的排放.特别是HQ+DCD处理,其N2O和CH4排放总量分别约为对照的1/3和1/2.而在施麦秸粉后,该处理的N2O排放总量为对照的1/2,但CH4排放总量却较少差别.不论是N2O还是CH4的排放总量,施麦秸粉的都比未施的高出1倍和更多.因此,单从土壤源温室气体排放的角度看,将未腐熟的有机物料与尿素共施,并不是一种适宜的施肥制度.供试土壤的N2O排放通量,与水稻植株的NO-3N含量和土表水层中的矿质N量分别呈显著的指数正相关和线性正相关;CH4的排放通量则与水稻植株的生长量和土表水层中的矿质N量呈显著的线性负相关.在N2O与CH4的排放间,未施麦秸粉时存在着定量的相互消长关系;施麦秸粉后,虽同样存在所述关系,但难以定量化.  相似文献   

11.
Nitrous oxide production was measured in intact cores taken from active pasture and old-growth forest Inceptisols in the Atlantic Lowlands of Costa Rica. Following additions of aqueous KNO3 or glucose, or the two combined amendments, the cores were incubated in the laboratory to determine if N2O production rates were either N-limited or C-limited in the two land use types. Differences in rates of denitrification (N22O + N2 production) among amended forest and pasture soils were determined by addition of 10% C2H2.The forest soils were relatively insensitive to all amendment additions, including the acetylene block. Forest N2O production rates among the treatments did not differ from the controls, and were consistently lower than those of the pasture soils. With the addition of glucose plus nitrate to the forest soils, production of N2O was three times greater than the controls, although this increase was not statistically significant. On the other hand, the pasture soils were definitely nitrogen-limited since N2O production rates were increased substantially beyond controls by all the amendments which contained nitrate, despite the very low N level (5 mg N kg–1 soil) relative to typical fertilizer applications. With respect to the nitrate plus glucose plus acetylene treatment, denitrification was high in the pasture soils; N2O production in the presence of C2H2 was 150% of the rate of N2O production measured in the absence of the acetylene block. The results are discussed in relation to the effects of agricultural land use practices and subsequent impacts of disturbance on N2O release.  相似文献   

12.
设置对照(CT)、增温5 ℃(W)、隔离50%降雨(P)和增温5 ℃+隔离50%降雨(WP)4种处理,以相关功能基因作为标志物,研究增温和隔离降雨影响亚热带森林生态系统土壤N2O通量变化的途径.结果表明: 隔离降雨显著降低了土壤铵态氮浓度;增温显著降低了土壤N2O通量和土壤反硝化势.增温处理(W)和降雨处理(P)的土壤微生物生物量氮(MBN)均显著低于对照(CT),AOA amoA基因丰度与MBN和铵态氮含量之间呈显著负相关,但与土壤硝化势和土壤N2O通量没有显著相关性.路径分析显示,反硝化势直接显著影响土壤N2O通量,而微生物生物量磷(MBP)和增温则通过直接影响反硝化势来间接影响土壤N2O通量.温度可能是影响亚热带森林土壤N2O通量的主要驱动因素,全球变暖可能会减少亚热带森林土壤的N2O排放.  相似文献   

13.
过量施肥对设施菜田土壤菌群结构及N2O产生的影响   总被引:1,自引:0,他引:1  
【背景】N_2O是一种很强的温室气体,其温室效应强度大约是CO_2的265倍。土壤氮肥施加量是影响N_2O排放的重要因素,而厌氧条件下微生物反硝化则是N_2O产生的重要途径。【目的】研究过量施肥条件下蔬菜大棚土壤菌群结构变化及其对N_2O气体排放的影响。【方法】利用自动化培养与实时气体检测系统(Robot)监测土壤厌氧培养过程中N_2O和N_2排放通量,比较过量施肥和减氮施肥模式下土壤N_2O排放模式的差异。通过Illumina二代测序平台对这2种不同施肥处理的土壤微生物群落进行高通量测序,研究不同施肥量对土壤菌群组成的影响。【结果】过量施肥土壤中硝酸盐的含量大约是减氮施肥土壤的2倍,通过添加硝酸盐使2种土壤的硝酸盐含量均为60 mg/kg或为200 mg/kg时,过量施肥土壤在厌氧培养前期N_2O气体的产生量及产生速度都明显高于减氮施肥土壤。另外,过量施肥导致土壤菌群结构发生显著改变,并且降低了土壤微生物的多样性。相对于减氮施肥,过量施肥方式富集了Rhodanobacter属的微生物。PICRUSt预测结果显示,传统施肥没有显著改变反硝化功能基因相对丰度。【结论】长期过量氮肥施用显著增加了土壤N_2O的排放,可能原因是施肥改变了包括氮转化相关微生物在内的土壤菌群组成,从而影响了土壤N_2O气体的形成与还原过程。  相似文献   

14.
The effect of nitrate and ammonium application (0, 50, 100 and 150 mg N kg-1 soil) was studied in an incubation experiment. Four Belgian soils, selected for different soil characteristics, were used. The application of both nitrate and ammonium caused an increase of the NO and N2O emission. The NO production from nitrate and ammonium was found to be of the same order of magnitude. At low pH the NO production was found to be highest from nitrate, at higher pH values the production was found to be higher from ammonium. This seems to be the result of the negative effect of low pH on nitrification.The ANOVA analysis was carried out to separate the effect of the form of nitrogen, quantily of N applied and soil characteristics. The total production of NO was found to depend for 97% on the soil characteristics and for 3% on the quantity of N added. The total N2O production depended for 100% on the soil characteristics.Stepwise regression analysis showed that the total NO production was best predicted by a combination of the factors CaCO3 content and NH4 + concentration in the soil. Total N2O production was best described by a combination of CaCO3, water soluble carbon (WSC) and sand-content.The N2O/NO ratio was found to be highly variable, indicating that their productions react differently to changes in conditions, or are partly independent.It may be concluded that to NO and N2O from soils both nitrification and denitrification may be equally important, their relative importance depending on local conditions such as substrate availability, water content of the soil etc. However, the NO production seems to be more nitrification dependent than the N2O production. ei]{gnE}{fnMerckx}{edSection editor}  相似文献   

15.
Quantification of harmful nitrous oxide (N(2)O) emissions from soils is essential for mitigation measures. An important N(2)O producing and reducing process in soils is denitrification, which shows deceased rates at low pH. No clear relationship between N(2)O emissions and soil pH has yet been established because also the relative contribution of N(2)O as the denitrification end product decreases with pH. Our aim was to show the net effect of soil pH on N(2)O production and emission. Therefore, experiments were designed to investigate the effects of pH on NO(3)(-) reduction, N(2)O production and reduction and N(2) production in incubations with pH values set between 4 and 7. Furthermore, field measurements of soil pH and N(2)O emissions were carried out. In incubations, NO(3)(-) reduction and N(2) production rates increased with pH and net N(2)O production rate was highest at pH 5. N(2)O reduction to N(2) was halted until NO(3)(-) was depleted at low pH values, resulting in a built up of N(2)O. As a consequence, N(2)O:N(2) production ratio decreased exponentially with pH. N(2)O reduction appeared therefore more important than N(2)O production in explaining net N(2)O production rates. In the field, a negative exponential relationship for soil pH against N(2)O emissions was observed. Soil pH could therefore be used as a predictive tool for average N(2)O emissions in the studied ecosystem. The occurrence of low pH spots may explain N(2)O emission hotspot occurrence. Future studies should focus on the mechanism behind small scale soil pH variability and the effect of manipulating the pH of soils.  相似文献   

16.
Nitrogen loss from grassland on peat soils through nitrous oxide production   总被引:2,自引:0,他引:2  
Koops  J.G.  van Beusichem  M.L.  Oenema  O. 《Plant and Soil》1997,188(1):119-130
Nitrous oxide (N2O) in soils is produced through nitrification and denitrification. The N2O produced is considered as a nitrogen (N) loss because it will most likely escape from the soil to the atmosphere as N2O or N2. Aim of the study was to quantify N2O production in grassland on peat soils in relation to N input and to determine the relative contribution of nitrification and denitrification to N2O production. Measurements were carried out on a weekly basis in 2 grasslands on peat soil (Peat I and Peat II) for 2 years (1993 and 1994) using intact soil core incubations. In additional experiments distinction between N2O from nitrification and denitrification was made by use of the gaseous nitrification inhibitor methyl fluoride (CH3F).Nitrous oxide production over the 2 year period was on average 34 kg N ha-1 yr-1 for mown treatments that received no N fertiliser and 44 kg N ha-1 yr-1 for mown and N fertilised treatments. Grazing by dairy cattle on Peat I caused additional N2O production to reach 81 kg N ha-1 yr-1. The sub soil (20–40 cm) contributed 25 to 40% of the total N2O production in the 0–40 cm layer. The N2O production:denitrification ratio was on average about 1 in the top soil and 2 in the sub soil indicating that N2O production through nitrification was important. Experiments showed that when ratios were larger than l, nitrification was the major source of N2O. In conclusion, N2O production is a significant N loss mechanism in grassland on peat soil with nitrification as an important N2O producing process.  相似文献   

17.
A mixed beech and spruce forest soil was incubated under potential denitrification assay (PDA) condition with 10% acetylene (C2H2) in the headspace of soil slurry bottles. Nitrous oxide (N2O) concentration in the headspace, as well as nitrate, nitrite and ammonium concentrations in the soil slurries were monitored during the incubation. Results show that nitrate disappearance rate was higher than N2O production rate with C2H2 blockage during the incubation. Sum of nitrate, nitrite, and N2O with C2H2 blockage could not recover the original soil nitrate content, showing an N imbalance in such a closed incubation system. Changes in nitrite and ammonium concentration during the incubation could not account for the observed faster nitrate disappearance rate and the N imbalance. Non-determined nitric oxide (NO) and N2 production could be the major cause, and the associated mechanisms could vary for different treatments. Commonly applied PDA measurement likely underestimates the nitrate removal capacity of a system. Incubation time and organic matter/nitrate ratio are the most critical factors to consider using C2H2 inhibition technique to quantify denitrification. By comparing the treatments with and without an antibiotic, the results suggest that microbial N uptake probably played a minor role in N balance, and other denitrifying enzymes but nitrate reductase could be substantially synthesized during the incubation.  相似文献   

18.
Elevated nitrogen deposition has increased tree growth, the storage of soil organic matter, and nitrate leaching in many European forests, but little is known about the effect of tree species and nitrogen deposition on nitrous oxide emission. Here we report soil N2O emission from European beech, Scots pine and Norway spruce forests in two study areas of Germany with distinct climate, N deposition and soils. N2O emissions and throughfall input of nitrate and ammonium were measured biweekly during growing season and monthly during dormant season over a 28 months period. Annual N2O emission rates ranged between 0.4 and 1.3 kg N ha?1 year?1 among the stands and were higher in 1998 than in 1999 due to higher precipitation during the growing season of 1998. A 2-way-ANOVA revealed that N2O fluxes were significantly higher (p<0.001) at Solling than at Unterlüß while tree species had no effect on N2O emissions. Soil texture and the amount of throughfall explained together 94% of the variance among the stands, indicating that increasing portions of silt and clay may promote the formation of N2O in wet forest soils. Moreover, cumulative N2O fluxes were significantly correlated (r2 = 0.60, p<0.001) with cumulative NO 3 ? fluxes at 10 cm depth as an indicator of N saturation, however, the slope of the regression curve indicates a rather weak effect of NO 3 ? fluxes on N2O emissions. N input by throughfall was not correlated with N2O emissions and only 1.6–3.2% of N input was released as N2O to the atmosphere. Our results suggest that elevated N inputs have little effect on N2O emissions in beech, spruce and pine forests.  相似文献   

19.
N2O production from denitrification in soils contributes to the enhanced greenhouse effect and the destruction of the stratospheric ozone. Ungulate grazing affects denitrification and the production of N2O. The short-term effect of grazing on denitrification and N2O production has been examined in several grassland ecosystems. However, the effects of long-term grazing have rarely been studied. We measured denitrification and N2O production during the 2005 and 2006 growing seasons in a long-term (17 years) experiment that had five grazing intensities (GI; 0.00, 1.33, 2.67, 4.00 and 5.33 sheep ha−1). We found that denitrification and N2O production rates were seasonally variable during the measurement period, with higher values observed in summer and lower values found in spring and autumn. The grazed treatments resulted in decreased denitrification and N2O production, primarily due to the reduced soil nitrate concentration and organic N content under the long-term grazing. This supported our hypothesis that long-term over-grazing suppresses denitrification and N2O production. Although significant differences in denitrification and N2O production were not found between the four GI, there was a general trend that cumulative denitrification and N2O production decreased as grazing intensity increased, especially in 2006. Lower N losses via denitrification and N2O production in the grazed plots, to some extent, may contribute to the mitigation of greenhouse gas emission and help to preserve soil N and ameliorate the negative impacts of grazing on plant growth, productivity, and ecological restoration processes in the temperate steppe in northern China.  相似文献   

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