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秸秆还田对灌溉玉米田土壤反硝化及N2O排放的影响 总被引：23，自引：3，他引：23
运用乙炔抑制技术研究了不同施氮水平下秸秆还田对灌溉玉米田土壤反硝化反应和氧化亚氮(N2O)排放的影响。结果表明,土壤反硝化速率及N2O的排放受氮肥施用、秸秆处理方式及其交互作用的显著影响。与秸秆燃烧相比,不施氮或低施氮水平时,秸秆还田可刺激培养初期反硝化反应速率及N2O排放,增加培养期间N2O平均排放通量;高施氮水平时,秸秆还田可降低反硝化反应速率及反硝化过程中的N2O排放。秸秆还田可降低反硝化中N2O/N2的比例。 相似文献
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采用田间试验研究了番茄地施用化学氮肥后的氨挥发、反硝化损失和N2O排放及其影响因素。氨挥发采用通气密闭室法测定，反硝化损失（N2＋N2O）采用乙炔抑制-土柱培养法测定，不加乙炔测定N2O排放。结果表明，番茄生长期间全部处理均未检测到氨挥发，其原因是土表氨分压低于检测灵敏度，较低的氨分压是由于表层土壤的铵态氮浓度和pH都不高所致。在番茄生长期间，对照区即来自有机肥和土壤本身的反硝化损失和N2O℃排放量相当高，反硝化损失总量高达N29．6kghm^-2，N2O排放量为N7．76kghm^-2。施用化学氮肥显著增加了反硝化损失和N2O排放，3个施用化学氮肥处理的反硝化损失变化在N40．8～46．1kghm^-2之间，占施入化肥氮量的5．50％～6．01％；N2O排放量为N13．6～17．6kghm^-2，占施入化肥氮量的2．62％～4．92％；与尿素相比，包衣尿素未能显著减低反硝化损失和N2O排放。施用尿素的处理在每次追肥后，耕层土壤均会出现NO3^--N高峰，继之的反硝化和N2O排放高峰。反硝化速率与土壤含水量呈极显著正相关。总的看来，番茄生长期间没有氨挥发，而硝化反硝化是氮素损失的重要途径之一。 相似文献
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森林土壤氧化亚氮排放对大气氮沉降增加的响应研究进展 总被引：1，自引：1，他引：1
森林土壤N2O来源于土壤氮素的氧化还原反应,硝化、反硝化、硝化细菌反硝化以及化学反硝化是其产生的四个关键过程。当前,氮素富集条件下森林土壤N2O排放存在硝化和反硝化主导作用之争,对大气氮沉降增加的响应模式以及微生物驱动机制尚不清楚。综述了森林土壤N2O来源的稳定性同位素拆分,森林土壤总氮转化和N2O排放对增氮的响应规律,增氮对N2O产生菌群落活性和组成的影响,并指出研究的薄弱环节与未来的研究重点。总体而言,森林土壤N2O排放对大气氮沉降增加的响应呈现非线性,包括初期无明显响应、中期缓慢增加和后期急剧增加三个阶段,取决于森林生态系统"氮饱和"程度。施氮会引起森林土壤有效氮由贫氮向富氮的转变,相应地改变了土壤硝化细菌和反硝化细菌群落丰度与组成,进而影响土壤N2O排放。由于森林土壤N2O排放监测、土壤总氮转化和N2O产生菌群落动态研究多为独立进行的,难以阐明微生物功能群与N2O排放之间的耦合关系。未来研究应该有机结合15N-18O标记和分子生物学技术,准确量化森林土壤N2O的来源,揭示森林土壤N2O排放对增氮的非线性响应机理。 相似文献
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利用膜进样质谱法测定不同氮肥用量下反硝化氮素损失 总被引：5，自引：2，他引：3
利用膜进样质谱仪(MIMS)测定了太湖流域典型稻田不同氮肥施用梯度下,土壤反硝化氮素损失量,同时也对氨挥发通量进行了观测。根据两年的田间试验结果得到:在常规施氮处理(N300)下,每年平均有54.8 kg/hm~2 N通过反硝化损失,有约54.0 kg/hm~2 N通过氨挥发损失,分别占肥料施用量的18.3%和18.0%,两者损失量相当。通过反硝化和氨挥发损失的氮素量随着氮肥用量增加而增加,田面水的NH_4~+-N、NO_3~–-N、DOC和pH浓度影响稻田土壤反硝化速率。在保产增效施氮处理(N_270)下,氮肥施用量比常规减少10%,水稻产量增加了5.5%,而通过反硝化和氨挥发损失的氮素量分别下降了1.1%和3.1%,氮肥利用率提高了约5.5%。在增施氮肥处理(N375)下,因作物产量增加使得氮肥利用率比N300增加,但通过氨挥发和反硝化的氮素损失量也最大。因此,通过综合集约优化田间管理措施,降低氮肥用量,可实现增产增效的目的。 相似文献
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低量施氮对小青菜生长和氮素损失的影响 总被引：1，自引：5，他引：1
采用田间试验和微区试验相结合,研究了低量施氮对小青菜(Brassica.chinensis)产量、氮肥利用率和氮素损失的影响,其中氮素总损失用15N示踪法测定,氨挥发用通气密闭室法测定,反硝化损失用乙炔抑制-原状土柱培养法测定,不加乙炔测定N2O排放。结果表明,施用氮肥显著增加了小青菜的产量和吸氮量,在75和150kg/hm2氮肥水平下,氮肥利用率分别为46.8%和39.4%。由于试验地土壤pH低(5.38),各处理的氨挥发均很低且差异不大,施用氮肥没有增加氨挥发。试验地土壤反硝化损失和N2O排放量较高,分别为N4.34kg/hm2/sup和N2.65kg/hm2,施用氮肥没有增加反硝化损失和N2O排放,表明氮源不是反硝化作用的限制因子。在N75和150kg/hm2两个施氮水平下,氮素回收率分别为103%和91.3%,并且土壤残留氮主要累积在020cm土层,表明肥料氮损失很少,这与氨挥发、反硝化损失较低的结果相吻合。 相似文献
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甲烷氧化微生物和氨氧化微生物均是既可以氧化甲烷(CH4)又可以氧化氨(NH3),氨氧化是硝化作用的限速步骤,也是好氧土壤氧化亚氮(N2O)排放的主要生物路径。选取内蒙古草原围封禁牧土壤为研究对象,利用稳定同位素核酸探针技术(DNA-SIP)探讨不同氮水平下土壤活性甲烷氧化微生物与硝化微生物及其相互作用机制。结果发现低氮添加促进甲烷氧化活性,而高氮添加抑制甲烷氧化活性;低氮和高氮添加均显著增强硝化活性。基于DNA-SIP的高通量测序结果发现Methylobacter MOB和Nitrosospira AOB/Nitrospira NOB分别是该土壤的主要活性甲烷氧化和硝化微生物。网络结构分析发现Methylobacter MOB和Nitrosospira AOB/Nitrospira NOB存在显著负相关关系,进一步证明活性甲烷氧化和硝化微生物之间存在竞争性相互作用。以上结果表明,氮素水平影响草原土壤甲烷氧化和硝化微生物的相互作用,研究结果为采取措施调控草原土壤CH4的汇和N2O... 相似文献
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施肥对夏玉米季紫色土N2O排放及反硝化作用的影响 总被引：9，自引：0，他引：9
采用原状土柱-乙炔抑制培养法研究了施肥对紫色土玉米生长季土壤N2O排放通量和反硝化作用的影响.结果表明:玉米季施肥显著增加土壤N2O排放和反硝化损失,同时,各施肥处理间N2O排放与反硝化损失量差异显著.猪厩肥、猪厩肥配施氮磷钾肥、氮肥、氮磷钾肥和秸秆配施氮磷钾肥等处理的土壤N,O排放量分别为3.01、2.86、2.51、2.19和1.88 kg hm-2,分别占当季氮肥施用量的1.63％、1.53％、1.30％、1.09％和0.88％,反硝化损失量分别为6.74、6.11、5.23、4.69和4.12 kg hm-2,分别占当季氮肥施用量的3.97％、3.55％、2.97％、2.61％和2.23％,不施肥土壤的N2O排放量和反硝化损失量仅为0.56和0.78 kg hm-2.施肥是紫色土玉米生长前期(2周内)土壤N2O排放和反硝化速率出现高峰的主要驱动因子,土壤铵态氮和硝态氮含量是影响土壤N2O排放、土壤硝化和反硝化作用的限制因子,土壤含水量是重要影响因子,降雨是主要促发因素.土壤N2O排放量与反硝化损失量的比值介于0.45 ～0.72之间,土壤反硝化损失量极显著高于土壤N2O排放量,说明土壤反硝化作用是紫色土玉米生长季氮肥损失的重要途径. 相似文献
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露地种植大白菜的氮肥效应与氮素损失研究 总被引：7，自引：0，他引：7
采用田间小区和微区试验,研究了施用化学氮肥在露地大白菜上的氮肥效应和氮素损失。氮素总损失用15N示踪法测定,氨挥发用通气密闭室法测定,反硝化损失用乙炔抑制原状土柱培养法测定,不加乙炔测定N2O排放。结果表明,施用化学氮肥增产显著,用差值法计算得到的氮肥利用率在25.3%4～7.2%之间,相应的示踪法氮肥利用率为18.1%2～4.6%。化学氮肥显著增加了氨挥发、反硝化和N2O排放等气态氮损失;其中氨挥发占施氮量的0.97%1～7.1%,反硝化占4.33%8～.55%,N2O排放在1.09%1～.63%之间变化。大白菜收获时9.2%～10.9%的标记尿素被淋洗到40.cm以下土层。试验期间尿素的氮素总损失达41.1%4～8.1%,以表观淋洗损失最为严重,其次是氨挥发,而反硝化损失最低。与普通尿素相比,包衣尿素明显降低了氨挥发。 相似文献
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硝化抑制剂烯丙基硫脲（ATU）对土壤硝化作用及温室效应的影响及机理尚不清楚。本研究采集典型旱地土壤,进行21天室内微宇宙培养,探究了氮肥与不同剂量ATU（分别为氮素用量的1%, 5%, 10%, 15%和20%）配施对土壤硝化作用及N2O和CO2排放通量的影响,并通过实时荧光定量PCR和高通量测序16S rRNA基因技术监测硝化微生物群落变化,同时与传统硝化抑制剂双氰胺（DCD）进行了保氮减排效果的对比。结果表明,与未施加氮肥的对照相比（CK）,单施氮肥（N）显著提高了土壤硝化强度并促进了N2O排放。DCD能显著抑制硝态氮和N2O的积累,抑制效率分别为68.6%和93.3%。而低浓度ATU对土壤硝化作用无影响,仅在高浓度具有抑制效应,且抑制效率最高仅为14.7%。所有ATU处理N2O排放量均显著降低,降幅为60.3～68.2%,仍远高于DCD处理。处理间N2O和CO2的综合温室效应强弱顺序为N>ATU+N>DCD+N≈CK,且不同ATU施用量处理之间差异不显著。相关分析发现氨氧化细菌（AOB）,而不是氨氧化古菌（AOA）和全程氨氧化细菌（Comammox）,与土壤硝态氮积累和N2O排放显著正相关,与土壤pH显著负相关。高通量测序结果表明Nitrosovibrio tenuis类型AOB对氮肥诱导的硝化过程起主导作用。除此之外,ATU和DCD还能显著提高Cupriavidus,并降低Patulibacter、Aeromicrobium、Actinomycetospora、Defluviicoccus和Acidipila等微生物属在群落中的相对丰度。该研究为深化土壤碳氮循环理论,合理使用硝化抑制剂以及减缓温室气体排放提供科学依据。 相似文献
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Summary A sandy soil amended with different forms and amounts of fertilizer nitrogen (urea, ammonium sulphate and potassium nitrate) was investigated in model experiments for N2O emission, which may be evolved during both oxidation of ammonia to nitrate and anaerobic respiration of nitrate. Since C2H2 inhibits both nitrification and the reduction of N2O to N2 during denitrification, the amount of N2O evolved in the presence and absence of C2H2 represents the nitrogen released through nitrification and denitrification.Results show that amounts of N2O-N lost from soils incubated anaerobically with 0.1% C2H2 and treated with potassium nitrate (23.1 µg N-NO
3
–
/g dry soil) exceeded those from soils incubated in the presence of 20% oxygen and treated with even larger amounts of nitrogen as urea and ammonium sulphate. This indicates that nitrogen losses by denitrification may potentially be higher than those occurring through nitrification. 相似文献
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Summary Field studies of the effects of different N fertilizers on emission of nitrous oxide (N20) from three Iowa soils showed that the N2O emissions induced by application of 180 kg ha–1 fertilizer N as anhydrous ammonia greatly exceeded those induced by application of the same amount of fertilizer N as aqueous ammonia or urea. On average, the emission of N2O-N induced by anhydrous ammonia was more than 13 times that induced by aqueous ammonia or urea and represented 1.2% of the anhydrous ammonia N applied. Experiments with one soil showed that the N2O emission induced by anhydrous ammonia was more than 17 times that induced by the same amount of N as calcium nitrate. These findings confirm indications from previous work that anhydrous ammonia has a much greater effect on emission of N2O from soils than do other commonly used N fertilizers and merits special attention in research relating to the potential adverse climatic effect of N fertilization of soils.Laboratory studies of the effect of different amounts of NH4OH on emission of N2O from Webster soil showed that the emission of N2O-N induced by addition of 100 g NH4OH-N g–1 soil represented only 0.18% of the N applied, whereas the emissions induced by additions of 500 and 1 000 g NH4OH-N g–1 soil represented 1.15% and 1.19%, respectively, of the N applied. This suggests that the exceptionally large emissions of N2O induced by anhydrous ammonia fertilization are due, at least in part, to the fact that the customary method of applying this fertilizer by injection into soil produces highly alkaline soil zones of high ammonium-N concentration that do not occur when urea or aqueous ammonia fertilizers are broadcast and incorporated into soil. 相似文献
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Application of membrane inlet mass spectrometry to directly quantify denitrification in flooded rice paddy soil 总被引：1，自引：0，他引：1
Denitrification has long been considered a major mechanism of N loss when N fertilizer is applied to flooded rice paddies. However, the direct determination of denitrification in soils is almost impossible because of the high atmospheric background of dinitrogen (N2). Dissolved N2 in a small water sample can be rapidly and precisely measured through membrane inlet mass spectrometry (MIMS). This study is the first to directly measure N2 flux through MIMS in flooded rice paddy plots that received different amounts of urea. Ammonia (NH3) volatilization was measured simultaneously to verify whether NH3 volatilization and denitrification are complementary loss mechanisms. The average cumulative N2–N loss measured by MIMS 21 days after fertilization was 4.7?±?1.7 % of the applied N, which was within the range of the reported values obtained by cumulative recovery of (N2 + N2O)–15N and 15N-balance technique. Underestimation or overestimation of denitrification can be prevented in MIMS given that N2 can be measured directly without 15N-labeled fertilizer. A good positive correlation was found between the dissolved in situ N2 concentrations of floodwater and the denitrification rates of intact soil cores. Urea incorporation reduced NH3 volatilization unlike surface broadcasting. However, urea incorporation significantly increased cumulative N2–N loss during the 21 days after fertilization. Correlation analysis showed that nitrate (NO3 ?–N) concentration in floodwater could be the primary restricting factor for soil denitrification in the experimental field. Results suggest that MIMS is a promising technique for the measurement of denitrification in a flooded rice paddy. 相似文献
14.
稻田反硝化速率测定方法研究进展 总被引：2，自引：0，他引：2
反硝化作用是淹水稻田肥料氮损失的主要途径之一。采用合适的反硝化测定方法是开展稻田反硝化作用研究的前提。然而，由于反硝化过程主要产物N2的大气背景值较高，以及反硝化作用具有高度时空异质性，淹水稻田反硝化作用损失氮量难以准确量化一直是阻碍科学评价稻田气态氮损失的关键难题。本文综述了研究稻田反硝化作用的4种方法（乙炔抑制法、15N同位素示踪法、密闭培养-氦气环境法和N2/Ar比值-膜进样质谱法），分析了这些方法各自的优缺点和适用性，并提出了稻田反硝化研究的参考建议，以期推动稻田反硝化的研究。 相似文献
15.
E.-A. Kaiser F. Eiland J. C. Germon M. A. Gispert O. Heinemeyer C. Henault A. M. Lind M. Maag E. Saguer O. Van Cleemput A. Vermoesen C. Webster 《植物养料与土壤学杂志》1996,159(6):541-547
N20 emissions and denitrification N-losses. precipitation, air temperature, soil moisture, bulk density and content of mineral N were monitored in 9 different agricultural soils in 6 European countries throughout the vegetation period (April to September) 1992 and 1993. N2O emissions and denitrification N-losses were log-normal distributed, reflecting high temporal changes. While small flux rates (< 2 g N ha?1 d?1) were detectable every day, high rates (> 10 g N ha?1 d?1) were measured after fertilization. An attempt to relate the emission variables to climate and soil variables was made through the use of correlation analysis. The mean N20 emissions from soil were significantly correlated with the soil properties clay, organic C and mineral N content and the amount of applied mineral N fertilizer. The best prediction of the N2O emission rates (r2 = 0.734) was achieved by multiple linear regression using the soil parameter clay and mineral N. Only 50% of the observed variation could be explained by the factors Corg and mineral N, which describe the substrate availability for microbial processes. No successful statistical model was found for the prediction of denitrification N-losses. 相似文献
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Nitrous oxide (N2O) emissions from grazed pastures constitute approximately 28% of total global anthropogenic N2O emissions. The aims of this study were to investigate the effect of inorganic N fertilizer application on fluxes of N2O, quantify the emission factors (EFs) for a sandy loam soil which is typical of large areas in Ireland and to investigate denitrification sensitivity to temperature. Nitrous oxide flux measurements from a cut and grazed pasture field for 1 year and denitrification laboratory incubation were carried out. The soil pH was 7.3 and had a mean organic C and N content at 0–20 cm of 44.1 and 4.4 g/kg dry weight, respectively. The highest observed peaks of N2O fluxes of 67 and 38.7 g N2O‐N per hectare per day were associated with times of application of inorganic N fertilizer. Annual fluxes of N2O from control and fertilized treatments were 1 and 2.4 kg N2O‐N per hectare, respectively. Approximately 63% of the annual flux was associated with N fertilizer application. Multiple regression analysis revealed that soil nitrate and the interaction between soil nitrate and soil water content were the main factors controlling N2O flux from the soil. The derived EF of 0.83% was approximately 66% of the IPCC default EF value of 1.25% as used by the Irish EPA to estimate greenhouse gases (GHGs) in Ireland. The IPCC‐revised EF value is 0.9%. A highly significant exponential regression (r2 = 0.98) was found between denitrification and incubation temperature. The calculated Q10 ranged from 4.4 to 6.2 for a temperature range of 10–25 °C and the activation energy was 47 kJ/mol. Our results show that denitrification is very sensitive to increasing temperature, suggesting that future global warming could lead to a significant increase in soil denitrification and consequently N2O fluxes from soils. 相似文献