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1.
硅胶管气样原位采集技术研究土壤N_2O浓度及通量变化 总被引：3，自引：1，他引：2
箱法被广泛用于监测土壤N_2O排放通量,但在原位采集高浓度土壤N_2O、全天候监测N_2O通量变化、动态研究土壤剖面N_2O的行为等方面存在弊端.本研究通过室内模拟硅胶管对N_2O的通透性,探索硅胶管用于原位采集土壤气样的理论可行性.田间试验设施用铵态氮肥(NH_4~+)、施用硝态氮肥(NO_3~-)及施用硝态氮肥加葡萄糖(NO_3~-+C)等3个处理,同时安置硅胶管和采样箱,验证硅胶管法在原位采集高浓度土壤N_2O气样、监测土壤N_2O浓度以及排放通量的实际效果,并与箱法进行比较.结果表明,硅胶管内外的N_2O气体经2.9 h达到95%的平衡,完伞能满足大田采样要求;用硅胶管法原位采集高浓度土壤N_2O气样的效果显著优于箱法采样.其浓度变化表现出明显的时间规律,浓度梯度法计算的N_2O排放通量与箱法测定结果呈显著正相关,但数值偏低;偏低的程度取决于采样位置和土壤中N_2O产生位置的匹配程度.建议采用埋于土壤表层的硅胶管计算地面N_2O排放通量,或在不同土层埋人硅胶管研究土壤剖面N_2O行为的时空变异. 相似文献
2.
粒径对冻融过程中加氮灌溉土壤N2O排放的影响 总被引：3，自引：2，他引：1
通过室内模拟的方法,研究了冻融过程潮土两种粒径（1 cm和0.25 mm）在加氮灌溉条件下N2O的排放通量,并且分析比较了3种氮素形态（铵态氮、硝态氮和酰胺态氮）和3种浓度（40、200和800 mg/L）对土壤N2O的排放通量的影响。结果表明：冻结前,除硝态氮浓度在大于200 mg/L时,细土N2O排放通量小于粗粒径土壤,其他氮素形态和浓度得到相反结果;冻结过程细土达到N2O稳定排放通量的时间要早于粗粒径土壤;融化后细土比粗粒径土壤早出现N2O排放峰,并且该峰值总体比粗粒径土壤小;随氮素浓度增加,粗粒径土壤3种氮素形态平均N2O累积排放量分别比细粒径土壤多45.46%、7.81%和46.87%。建议土壤在加氮灌溉时应尽量避免施加硝态氮肥,铵态氮肥的施用应尽量考虑降低浓度,并建议在灌溉越冬水且土壤冻结后耙碎大土块以减少N2O排放。 相似文献
3.
氮肥品种对亚热带土壤N2O排放的影响 总被引：8，自引：3，他引：5
以亚热带湿热地区红壤性旱地(SU),灌丛(GB),林地(QF)为研究对象,通过在30℃和60%WHC水分条件下,35 d的培养试验,研究了外源铵态氮输入对土壤N2O排放的影响。结果表明,对于pH较高的土壤SU(pH=6.27),施用硫铵、尿素和碳酸氢铵后,硝态氮累积量和N2O排放量均高于未施氮的处理,且随施N量增加而增加。对于酸性土壤GB(pH=4.82)和QF(pH=4.46),施用硫铵明显地抑制硝化作用,但却极大地促进N2O排放;施用尿素和碳酸氢铵对硝化作用有微弱的促进作用或无明显的影响,N2O的排放则略低于对照或无明显差异。酸性土壤中,加入不同类型的氮肥后,N2O排放量与硝态氮含量的比例与加入氮肥后测定的土壤pH具有显著的负相关关系。氮肥品种影响N2O排放量与硝态氮产生量比例的机理值得进一步研究。 相似文献
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5.
通过田间静态箱监测和DNDC模型模拟的方法,对比研究了崇明岛东滩蔬菜田在常规肥水管理和精确滴灌施肥方式下N2O的排放情况,从排放特征、全年通量、单位氮肥N2O损失率以及单位作物产量排放量等方面分析了不同肥水管理方式对旱田土壤N2O排放的影响。 结果表明,基于土壤和作物养分平衡管理的精确滴灌施肥技术,由于减少了氮肥施用量并改进了肥水分配方式,提高了肥料的利用效率,在保持农作物产量的基础上减少了N2O的排放。与常规肥水管理方式相比,滴灌施肥区2006年和2007年的N2O排放通量分别减少6.2和6.8 kg N·hm^-2·a^-1,单位氮肥N2O损失率明显降低,2006年和2007年单位产量排放量分别削减53.2％和58.9％。 相似文献
6.
华北春玉米田施用纳米增效氮肥的增产减排作用初探 总被引：2，自引：0，他引：2
采用静态箱自动采样监测系统,对生长季内华北平原春玉米田在不同施肥处理下（尿素U、纳米增效碳铵NA、纳米增效尿素NU和不施肥CK）土壤N2O排放通量进行监测,以寻求在相同施氮量条件下既增产又能减少N2O排放的施肥措施.结果表明,不同施肥处理下N2O排放通量存在显著差异（P＜0.05）,全生育期U、NU、NA和CK处理区的N2O排放总量依次为1.17、0.78、0.70、0.18kgN·hm-2,NA和NU分别比U减少了40％和33％的N2O排放;而玉米产量依次为NU＞ NA＞U＞CK,与U相比,NU和NA分别显著高出11％和9％的玉米产量（P＜0.05）.可见,与施用尿素相比,在玉米产量显著增加的前提下,纳米增效氮肥具有明显的减排效果. 相似文献
7.
N2O是重要的温室气体之一,由此引起的全球变暖和臭氧层破坏是当今重要的环境问题。采用遮光密闭箱和气相色谱法研究了氮肥施用对小麦地N2O释放和反硝化作用的影响。结果表明,小麦生长季节里,高氮、中氮以及不施氮处理N2O平均排放通量分别为2.71、2.42、1.97 gN.hm-.2d-1;尿素、硫酸铵、硝酸钾3种氮肥品种处理下,平均N2O排放通量分别为2.42、2.14、3.13 gN.hm-2.d-1。小麦生长季节里,高氮、中氮以及不施氮处理平均反硝化速率分别为4.91、4.50、1.67 gN.hm-.2d-1;尿素、硫酸铵、硝酸钾3种氮肥品种处理下,平均反硝化速率分别为4.50、3.68、5.29 gN.hm-.2d-1。氮肥施用明显促进了土壤-植物系统中N2O排放通量和反硝化作用,氮肥施用量水平和N2O排放通量、反硝化作用呈正相关。硝酸钾对N2O排放通量和反硝化作用贡献最大,硫酸铵最小。研究还表明,小麦地N2O释放和反硝化作用与季节有一定相关性,温度较高季节排放量及反硝化作用明显,反之则较弱。 相似文献
8.
有机无机肥料配合施用对设施菜田土壤N2O排放的影响 总被引：11，自引：3，他引：8
采用静态箱气相色谱法研究了有机无机肥料配合施用对设施菜田土壤N2O排放的影响。结果表明: 1）设施芹菜和番茄施基肥后57 d（灌溉后13 d）出现土壤N2O排放通量峰值,追肥后（施肥与灌溉同步）1 d出现土壤N2O排放通量峰值; 芹菜季和番茄季施用基肥后20 d内N2O排放量分别占当季总排放量的40%65%左右,是土壤N2O主要排放期。2）施用基肥后至定植灌水前各处理土壤N2O排放量逐渐降低,灌水后N2O排放通量迅速上升。各处理土壤N2O排放通量与土壤含水量之间呈显著相关,相关系数在0.43~0.72之间。3）土壤N2O排放主要发生在番茄季,番茄生育期各处理土壤N2O总排放量是芹菜生育期的3.1倍; 各处理土壤N2O排放通量与5 cm土层温度之间总体上呈显著相关,相关系数在0.40~0.58之间。4）设施菜田大幅减施化肥的有机无机肥配合施用模式可显著降低土壤N2O排放量和肥料损失率,芹菜季和番茄季土壤N2O排放量较习惯施肥处理分别降低66.3%和85.1%,肥料损失率分别降低45.2%和74.9%。5）等氮量投入时,施用秸秆较施用猪粪可有效降低土壤N2O排放,芹菜季和番茄季分别降低43.4%和74.2%。 相似文献
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施肥处理和环境因素对华北平原春玉米田N2O排放的影响——以山西晋中为例 总被引：2，自引：0，他引：2
采用静态箱自动采样监测系统,对生长季内华北平原春玉米田在不同施肥处理下（化肥、有机肥、有机无机配施和不施肥）的土壤N2O排放通量进行监测,分析各处理的土壤N2O排放量和变化规律,探讨土壤温度、水分和有效氮含量对土壤N2O排放通量的影响,并在相同施氮量条件下寻求既能增产又能减少N2O排放的施肥措施。结果表明：不同施肥处理下N2O排放通量存在显著差异（P〈0.05）,其中施肥处理的农田N2O-N排放总量为0.99～1.17kg.hm-2,占总施氮量的0.45%～0.55%;N2O通量与土壤铵态氮含量呈极显著正相关（P〈0.01）;土壤含水量是影响农田N2O排放的一个主要因子,N2O通量与土壤含水量呈显著正相关;在产量无显著下降的情况下,有机无机配施的减排效果最好。 相似文献
11.
To understand nitrous oxide (N2O) emissions from terrestrial ecosystems it is necessary to understand the processes leading to N2O production. Here, for the first time, results are presented which identify in situ the processes of N2O production in a temperate grassland soil. A small portion of the nitrogen (N) applied in the summer to the grassland soil was rapidly transported below the main rooting zone (>20 cm) and resulted in large N2O productions at depths of 20-50 cm. Preferential pathways must have been responsible for this movement because the soil conditions were not conducive to leaching by piston flow. The N2O was entirely produced by nitrate (NO3−) reduction which was surprising because the bulk soil was aerobic. Therefore, reduction processes can operate during times of the year when it is least expected and cause large N2O concentrations deep in the soil profile. 相似文献
12.
N2O and NO fluxes between a Norway spruce forest soil and atmosphere as affected by prolonged summer drought 总被引：2，自引：0，他引：2
Global change scenarios predict an increasing frequency and duration of summer drought periods in Central Europe especially for higher elevation areas. Our current knowledge about the effects of soil drought on nitrogen trace gas fluxes from temperate forest soils is scarce. In this study, the effects of experimentally induced drought on soil N2O and NO emissions were investigated in a mature Norway spruce forest in the Fichtelgebirge (northeastern Bavaria, Germany) in two consecutive years. Drought was induced by roof constructions over a period of 46 days. The experiment was run in three replicates and three non-manipulated plots served as controls. Additionally to the N2O and NO flux measurements in weekly to monthly intervals, soil gas samples from six different soil depths were analysed in time series for N2O concentration as well as isotope abundances to investigate N2O dynamics within the soil. N2O fluxes from soil to the atmosphere at the experimental plots decreased gradually during the drought period from 0.2 to −0.0 μmol m−2 h−1, respectively, and mean cumulative N2O emissions from the manipulated plots were reduced by 43% during experimental drought compared to the controls in 2007. N2O concentration as well as isotope abundance analysis along the soil profiles revealed that a major part of the soil acted as a net sink for N2O, even during drought. This N2O sink, together with diminished N2O production in the organic layers, resulted in successively decreased N2O fluxes during drought, and may even turn this forest soil into a net sink of atmospheric N2O as observed in the first year of the experiment. Enhanced N2O fluxes observed after rewetting up to 0.1 μmol m−2 h−1 were not able to compensate for the preceding drought effect. During the experiment in 2006, with soil matric potentials in 20 cm depth down to −630 hPa, cumulative NO emissions from the throughfall exclusion plots were reduced by 69% compared to the controls, whereas cumulative NO emissions from the experimental plots in 2007, with minimum soil matric potentials of −210 hPa, were 180% of those of the controls. Following wetting, the soil of the throughfall exclusion plots showed significantly larger NO fluxes compared to the controls (up to 9 μmol m−2 h−1 versus 2 μmol m−2 h−1). These fluxes were responsible for 44% of the total emission of NO throughout the whole course of the experiment. NO emissions from this forest soil usually exceeded N2O emissions by one order of magnitude or more except during wintertime. 相似文献
13.
Gaseous and leaching nitrogen losses from no-tillage and conventional tillage systems following surface application of cattle manure 总被引：2，自引：0，他引：2
M.S. Mkhabela A. Madani R. Gordon D. Burton D. Cudmore A. Elmi W. Hart 《Soil & Tillage Research》2008,98(2):187-199
Previous studies have demonstrated inconsistent results on the impact of tillage systems on nitrogen (N) losses from field-applied manure. This study assessed the impact of no-tillage (NT) and conventional tillage (CT) systems on gaseous N losses, N2O:N2O + N2 ratios and NO3−-N leaching following surface application of cattle manure. The study was undertaken during the 2003/2004 and 2004/2005 seasons at two field sites in Nova Scotia namely, Streets Ridge (SR) in Cumberland County and the Bio-environmental Engineering Centre (BEEC) in Truro. Results showed that the NT system had higher (p < 0.05) NH3 losses than CT. Over the two seasons, manure incorporation in CT reduced NH3 losses on average by 86% at SR and 78% at BEEC relative to NT. At both sites and during both seasons, denitrification rates and N2O fluxes in NT were generally higher than in CT plots, presumably due to higher soil water and organic matter content in NT. Over the two seasons, mean denitrification rates at SR were 239 and 119 g N ha−1 d−1, while N2O fluxes were 120 and 64 g N ha−1 d−1 under NT and CT, respectively. At BEEC mean denitrification rates were 114 and 71 g N ha−1 d−1, while N2O fluxes were 52 and 27 g N ha−1 d−1 under NT and CT, respectively. Conversely, N2O:N2O + N2 ratios were lower in NT than CT suggesting more complete reduction of N2O to N2 under NT. When averaged across all soil depths, NO3−-N was higher (p < 0.05) in CT than NT. Nitrate-N decreased with depth at both sites regardless of tillage. In most cases, NO3−-N was higher under CT than NT at all soil depths. Similarly, flow-weighted average NO3−-N concentrations in drainage water were generally higher under CT. This may be partly attributed to higher denitrification rates under NT. Therefore, NT may be a viable strategy to remove NO3−-N from the soil, and thus, reduce NO3−-N contamination of groundwater. However, it should be noted that while the use of NT reduces NO3−-N leaching it may come with unintended environmental tradeoffs, including increased NH3 and N2O emissions. 相似文献
14.
Xingren Liu Yunshe Dong Jianqiang Ren Qingzhong Zhang 《Soil Science and Plant Nutrition》2013,59(4):416-423
Nitrous oxide (N2O) flux in the semi-arid Leymus chinensis (Trin.) Tzvel. grassland in Inner Mongolia, China was measured for two years (from January 2005 to December 2006) with the enclosed chamber technique. The measurements were made twice per month in the growing season and once per month in the non-growing season. To evaluate the effect of aboveground vegetation on N2O emission, the ecosystem N2O flux over the grassland was measured, and concurrently soil N2O flux was measured after the removal of all the aboveground biomass. The possible effect of water-heat factors on N2O fluxes was statistically examined. The ecosystem N2O flux ranged from 0.21 to 0.26?kg nitrous oxide-nitrogen (N2O–N) ha? 1 year? 1, indicating that the Leymus chinensis grassland of Inner Mongolia was a source for the atmospheric N2O. There was no significant difference between the ecosystem N2O flux and the soil N2O flux. The ecosystem N2O flux was under similar environmental control as the soil N2O flux. Soil moisture was the primary driving factor of the N2O fluxes in the growing season of both years; the changes in water–filled pore space (WFPS) of soil surface layers could explain 45–67% of the variations in N2O fluxes. The high seasonal variation of the N2O fluxes in the growing seasons was regulated by the distribution of effective rainfall, rather than the precipitation intensity. While in the non-growing season, the N2O fluxes were restricted much more by air temperature or soil temperature, and 83–85% of the variations of the N2O fluxes were induced by changes in temperature conditions. 相似文献
15.
Nitrous oxide (N2O) is a greenhouse gas and agricultural soils are major sources of atmospheric N2O. Its emissions from soils make up the largest part in the global N2O budget. Research was carried out at the experimental fields of the Leibniz-Institute of Agricultural Engineering Potsdam-Bornim (ATB). Different types (mineral and wood ash) and levels (0, 75 and 150 kg N ha−1) of fertilization were applied to annual (rape, rye, triticale and hemp) and perennial (poplar and willow) plants every year. N2O flux measurements were performed 4 times a week by means of gas flux chambers and an automated gas chromatograph between 2003 and 2005. Soil samples were also taken close to the corresponding measuring rings. Soil nitrate and ammonium were measured in soil extracts.N2O emissions had a peak after N fertilization in spring, after plant harvest in summer and during the freezing–thawing periods in winter. Both fertilization and plant types significantly altered N2O emission. The maximum N2O emission rate detected was 1081 μg N2O m−2 h−1 in 2004. The mean annual N2O emissions from the annual plants were more than twofold greater than those of perennial plants (4.3 kg ha−1 vs. 1.9 kg ha−1). During January, N2O fluxes considerably increased in all treatments due to freezing–thawing cycles. Fertilization together with annual cropping doubled the N2O emissions compared to perennial crops indicating that N use efficiency was greater for perennial plants. Fertilizer-derived N2O fluxes constituted about 32% (willow) to 67% (rape/rye) of total soil N2O flux. Concurrent measurements of soil water content, NO3 and NH4 support the conclusion that nitrification is main source of N2O loss from the study soils. The mean soil NO3-N values of soils during the study for fertilized soils were 1.6 and 0.9 mg NO3-N kg−1 for 150 and 75 kg N ha−1 fertilization, respectively. This value reduced to 0.5 mg NO3-N kg−1 for non-fertilized soils. 相似文献
16.
Barbara Chaves Stefaan De Neve Maria del Carmen Lillo Cabrera Pascal Boeckx Oswald Van Cleemput Georges Hofman 《Biology and Fertility of Soils》2005,41(6):411-418
Manipulating the N release from high-N crop residues by simultaneous mixing of these residues with organic biological waste (OBW) materials seems to be a possible method to reduce NO3– leaching. The aim of this study was to examine whether the incorporation of OBW materials together with a high-N crop residue (celery) had also an effect on N2O emission from horticultural soil under short-term and optimised laboratory conditions. A sandy loam soil and celery residues were mixed with different OBW materials and brought into PVC tubes at 80% water-filled pore space and 15°C. Every 2.5 h, a gas sample was taken and analysed by gas chromatography for its N2O concentration. The soil amended with only celery residues had a cumulative N2O emission of 9.6 mg N kg–1 soil in 50 h. When the celery residues were mixed with an OBW material, the N2O emission was each time lower than the emission from the celery-only treatment (between 3.8 and 5.9 mg N kg–1 soil during maximum 77 h), except with paper sludge (17.2 mg N kg–1 soil in 100 h). The higher N2O emission from the paper sludge treatment was probably due to its unusually low C:N ratio. Straw, green waste compost 1 (GWC1) and 2 (GWC2), saw dust, and tannic acid reduced the N2O emission of the celery treatment by 40 to 60%. Although the N2O reduction potential can be expected to be lower and with differing dynamics under field conditions, this study indicates that apart from reducing NO3– leaching, OBW application may at the same time reduce N2O emissions after incorporation of high-N crop residues. 相似文献
17.
《Communications in Soil Science and Plant Analysis》2012,43(14):1763-1777
A 56-day aerobic incubation experiment was performed with 15-nitrogen (N) tracer techniques after application of wheat straw to investigate nitrate-N (NO3-N) immobilization in a typical intensively managed calcareous Fluvaquent soil. The dynamics of concentration and isotopic abundance of soil N pools and nitrous oxide (N2O) emission were determined. As the amount of straw increased, the concentration and isotopic abundance of total soil organic N and newly formed labeled particulate organic matter (POM-N) increased while NO3-N decreased. When 15NO3-N was applied combined with a large amount of straw at 5000 mg carbon (C) kg?1 only 1.1 ± 0.4 mg kg?1 NO3-N remained on day 56. The soil microbial biomass N (SMBN) concentration and newly formed labeled SMBN increased significantly (P < 0.05) with increasing amount of straw. Total N2O-N emissions were at levels of only micrograms kg?1 soil. The results indicate that application of straw can promote the immobilization of excessive nitrate with little emission of N2O. 相似文献
18.
《Soil Science and Plant Nutrition》2013,59(5):786-793
Abstract Laboratory incubations were conducted to investigate nitrous oxide (N2O) production from a subtropical arable soil (Typic Plinthodults) incubated at different soil moisture contents (SMC) and with different nitrogen sources using a 10% (v/v) acetylene (C2H2) inhibitory technique at 25°C. The production of N2O and CO2 was monitored during the incubations and changes in the contents of KCl-extractable NO? 3-N and NH+ 4-N were determined. The production of N2O increased slightly with an increase in SMC from 40% water-holding capacity (WHC) to 70% WHC, but increased dramatically at 100% WHC. After incubation the NO? 3-N content increased even at a SMC of 100% WHC. At a SMC of 100% WHC, the addition of NH+ 4-N promoted the production of N2O and CO2, whereas the addition of NO? 3-N decreased N2O production. Compared with the incubation without C2H2, the presence of C2H2 increased NH+ 4-N content, but decreased NO? 3-N content, and there was no significant difference in N2O production. These results indicate that heterotrophic nitrification contributes to N2O production in the soil. 相似文献
19.
利用15N同位素标记方法,研究在两种水分条件即60％和90％ WHC下,添加硝酸盐(NH4NO3,N 300 mg kg-1)和亚硝酸盐(NaNO2,N 1 mg kg-1)对中亚热带天然森林土壤N2O和NO产生过程及途径的影响.结果表明,在含水量为60％ WHC的情况下,高氮输入显著抑制了N2O和NO的产生(p＜0.01);但当含水量增为90％ WHC后,实验9h内抑制N2O产生,之后转为促进.所有未灭菌处理在添加NO2-后高氮抑制均立即解除并大量产生N2O和NO,与对照成显著差异(p＜0.01),在60％ WHC条件下,这种情况维持时间较短(21 h),但如果含水量高(90％ WHC)这种情况会持续很长时间(2周以上),说明水分有效性的提高和外源NO2-在高氮抑制解除中起到重要作用.本实验中N2O主要来源于土壤反硝化过程,而且加入未标记NO2-后导致杂合的N2O(14N15NO)分子在实验21 h内迅速增加,表明这种森林土壤的反硝化过程可能主要是通过真菌的“共脱氮”来实现,其贡献率可多达80％以上.Spearman秩相关分析表明未灭菌土壤NO的产生速率与N2O产生速率成显著正相关性(p＜0.05),土壤含水量越低二者相关性越高.灭菌土壤添加NO2-能较未灭菌土壤产生更多的NO,但却几乎不产生N2O,表明酸性土壤的化学反硝化对NO的贡献要大于N2O. 相似文献