石灰性紫色土硝化作用及硝化微生物对不同氮源的响应

土壤中发生的硝化作用是对p H高度敏感的典型过程。本文采用室内恒温培养法,结合定量PCR和高通量测序,研究石灰性紫色土硝化作用以及氨氧化细菌(Ammonia-oxidizing bacteria,AOB)、氨氧化古菌(Ammonia-oxidizing archaea,AOA)、亚硝酸盐氧化细菌(Nitrite-oxidizing bacteria,NOB)的丰度与群落结构对不同氮源的响应。结果表明:不同氮源均刺激土壤硝化作用的发生,CO(NH2)2处理下的净硝化速率最大,约是CK处理的4.76倍,(NH_4)2SO4和NH_4Cl处理下的净硝化速率分别为N 3.88和3.34 mg kg-1d-1。相比于(NH_4)2SO4和CO(NH2)2处理,NH_4Cl处理降低了硝态氮的累积量,抑制了铵态氮的减少量。AOB amo A基因拷贝数在28 d培养过程中变化显著(p0.05),在(NH_4)2SO4和CO(NH2)2处理中呈先增长后降低趋势,在NH_4Cl处理中呈持续增长趋势;而AOA amo A基因拷贝数无显著变化(p0.05)。说明石灰性紫色土硝化作用的主要推动者是AOB,而不是AOA。在28 d培养过程中,亚硝酸盐氧化细菌占总微生物的比例高于氨氧化细菌和古菌,意味着石灰性紫色土中可能存在全程氨氧化微生物(Comammox)。高通量测序的结果表明:石灰性紫色土中AOB的优势种群为亚硝化螺菌Nitrosospira Cluster 3,AOA的优势种群是土壤古菌Group 1.1b,NOB的优势种群是硝化螺菌Nitrospira。     

水氮耦合对设施农田土壤自养和异养硝化作用的影响

水氮措施影响设施土壤氮素的转化及硝化微生物活性,但水氮耦合对设施土壤自养和异养硝化作用差异的影响尚不明确。以连续8年设施水氮耦合田间定位试验土壤为研究对象,控制不同土壤田间持水量(WHC)(40%WHC、60%WHC和80% WHC)进行室内微宇宙培养试验,通过添加乙炔抑制剂抑制自养硝化途径,研究水氮耦合对设施土壤自养和异养硝化速率及参与自养硝化的氨氧化微生物的影响,分析氨氧化微生物氨氧化古细菌(AOA)和氨氧化细菌(AOB)对自养硝化作用的贡献。结果表明,水氮耦合下,不同硝化途径NH4+-N、NO^3--N含量以及参与自养硝化的AOA amoA和AOB amoA基因拷贝数均有显著差异。无乙炔培养7 d后,NO^3--N含量显著增加,而NH4+-N含量显著降低,AOA amoA和AOB amoA的基因丰度显著增加。添加乙炔后,NO^3--N、NH4+-N含量基本保持恒定,AOA amoA和AOB amoA基因丰度显著减少。水氮耦合显著影响自养和异养硝化速率,冗余分析(RDA)表明,NH4+-N含量、AOB amoA、NO^3--N-C2H2、AOA amoA可分别解释自养和异养硝化速率变异的68.9%、34.9%、32.8%和24.4%。设施土壤存在自养硝化和异养硝化两种途径,60%～80%WHC各施氮处理均以自养硝化为主,占总硝化速率的65%～86%;仅40%WHC下,氮纯养分量300和525 kg·hm-2处理以异养硝化为主,占总硝化速率的61%～77%。AOB和AOA共同驱动自养硝化,且AOB贡献更大。     

不同水分条件下土壤N2O排放的动力学方程模拟

[目的]水分对土壤N₂O排放有重要影响。运用混合动力学方程模拟不同水分条件下土壤N₂O累积排放的过程,分析土壤水分对N₂O产生途径的影响及其变化规律,为通过改善土壤管理降低N₂O气体排放提供理论和实践指导。[方法]通过室内培养试验,研究了不同水分条件[40%WHC,60%WHC,80%WHC,100%WHC和淹水处理,WHC(田间持水量)]下土壤N₂O排放特征、硝铵态氮含量和氧气消耗动态变化。[结果](1)N₂O排放速率24 h时达到最大,淹水处理[3.46μg/(kg·h)]是其他处理的54.5～178.9倍。(2)土壤N₂O累积排放量均随着培养时间的延长而增加,淹水处理的快速上升阶段为前48 h,而其他处理为前96 h。培养结束时的土壤N₂O累积排放量,淹水处理(44.6μg/kg)分别是40%WHC,60%WHC,80%WHC和100%WHC的67.1,29.2,20.8,10.4倍。(3)除淹水条件下,伪...     

不同生育期苹果园土壤氨氧化微生物丰度研究

【目的】大量施氮引起的土壤酸化问题已严重制约苹果的安全生产。氨氧化微生物驱动的土壤硝化作用是土壤氮素循环的重要环节,探析苹果园土壤中氨氧化微生物氨单加氧酶基因(amoA)丰度与土壤硝化强度(Potential Nitrification,PN)和土壤理化性质的相关性,有助于评价土壤氨氧化微生物类群在苹果园土壤生态系统中的作用。【方法】本研究以辽宁省丹东东港地区‘寒富’苹果园土壤为研究对象,采用实时荧光定量PCR(Real-time PCR)技术,检测苹果树不同生育时期, 4月28日(萌芽期)、 7月24日(新梢停长期)、 10月23日(落叶期)的两个苹果园(分别编号为D1和D2)的土壤理化性质、 土壤硝化强度、 氨氧化古菌(Ammonia-oxidizing archaea, AOA)和氨氧化细菌(Ammonia-oxidizing bacteria, AOB)的amoA基因丰度,并分析了氨氧化微生物丰度与土壤理化性质和土壤硝化强度之间的关系。【结果】不同生育时期‘寒富’苹果园土壤理化因子差异较大。所有供试土壤的硝态氮(NO-3-N)、 速效磷(AP)和速效钾(AK)含量在4月份最高,铵态氮(NH+4-N)含量在7月最高,NO-3-N、 NH+4-N、 AP和AK含量在10月多为最低。且所有供试土壤pH值均在4.25~6.09之间。同一生育时期内,D2土壤pH均显著高于D1土壤,但其NO-3-N和NH+4-N含量则不同程度地低于D1土壤。不同采样时期的果园土壤硝化强度随季节变化表现出先降后增的趋势,除7月D2土壤硝化强度显著高于D1土壤外,4月与10月D2土壤硝化强度均显著低于D1土壤。尽管不同采样时期的土壤AOA与AOB丰度随生育期而各异,所有供试土壤中AOA丰度均显著高于AOB丰度。同一时期内,D2土壤AOA和AOB丰度均显著高于D1土壤。尽管土壤pH、 NO-3-N与AOA、 AOB均表现出显著相关性,土壤PN仅与AOA丰度明显正相关。【结论】长期施肥导致苹果园土壤pH值降低,pH值的改变是影响AOA与AOB丰度的重要因子,果园土壤的硝化过程主要由AOA来完成,土壤硝化强度与季节变化引起的温度和土壤环境因子等的改变密切相关。苹果园无机氮肥混合有机肥的施入,同时结合自然生草、 人工刈割等管理制度,在一定程度上可改变土壤氮素的含量与种类,减缓土壤酸化。     

有机碳氮添加对酸性森林土壤氨氧化过程的影响

以亚热带酸性森林土壤为研究对象,开展了微宇宙室内培养实验,设置了有机碳和有机氮添加处理,分析了土壤硝化活性和氨氧化古菌(Ammonia-oxidizing archaea,AOA)、氨氧化细菌(Ammonia-oxidizing bacteria,AOB)的功能基因丰度,研究了外源有机碳和有机氮对酸性森林土壤氨氧化过程的影响规律。结果表明:外源有机氮添加显著刺激了酸性森林土壤硝化活性,乙炔抑制实验表明自养氨氧化对酸性森林土壤硝化过程的贡献率90%。有机碳添加对土壤硝化活性未有显著影响,同时添加有机碳和无机铵态氮也未显著提高土壤硝化活性,而外源有机氮添加提高了土壤矿化速率并导致土壤NH3浓度升高,可能是土壤硝化活性、AOA和AOB数量显著增加的主要原因。     

施肥和淹水管理对水稻土氨氧化微生物数量的影响

全程氨氧化细菌(Completeammoniaoxidizers,Comammox)的发现被认为是氮循环研究的重要进展,但复杂土壤中Comammox与氨氧化细菌(Ammonia-oxidizing bacteria, AOB)和氨氧化古菌(Ammonia-oxidizingarchaea,AOA)共存的环境驱动机制尚不清楚。针对紫色水稻土长期定位试验的植稻淹水(夏季植稻施肥并且全年淹水)管理、休耕冬干(不植稻、不施肥,仅在夏季植稻期间淹水,冬季排水落干)管理,研究了施肥和水分管理对水稻土硝化潜势及氨氧化微生物类群丰度的影响。结果表明,植稻淹水土壤的硝化潜势显著高于休耕冬干,分别为25.0 mg·kg~(-1)·d~(-1)、2.11mg·kg~(-1)·d~(-1),相差可达12倍之多。实时荧光定量PCR分析表明,两种管理方式下水稻土中均能检测到Comammox、AOA和AOB,并且其数量均为ComammoxAOAAOB。植稻淹水中Comammox丰度分别为AOA的8.5倍、AOB的77.3倍,而休耕冬干中Comammox丰度分别为AOA的4.1倍、AOB的490.3倍。相比于休耕冬干管理,植稻淹水刺激了Comammox分支A(Clade A)、AOA和AOB的生长,三者增长倍数分别为9、3、42,但Comammox分支B(Clade B)的降幅高达两倍之多。这些结果表明,与休耕冬干管理相比,28年长期植稻淹水,可能导致水稻土氨氧化微生物类群长期处于低O_2胁迫,并选择性促进了Comammox Clade A和AOA的生长,高强度施肥则显著促进了AOB生长,而Comammox Clade A和AOA则具有更广的铵态氮底物适应范围。未来应通过稳定性同位素示踪DNA技术,明确水稻土中数量上占优势的Comammox的功能意义及其与AOA和AOB的相对重要性。     

氮肥施加条件下增温对硝化菌活性和丰度的影响

温度在多种生物地球化学过程中起到关键的调节作用,是影响土壤硝化作用和微生物分布的重要因素之一。硝化过程的第1个步骤由氨氧化细菌(AOB)和氨氧化古菌(AOA)催化,然而,不同施氮量下,增温对硝化菌活性和丰度的影响尚不清楚。本研究基于2008年10月起设立于太行山山前平原的长期增温试验平台(高于地表2m的红外加热器使土壤温度升高1.5℃),于2018年5月对不施氮(N0)和施氮[N1,240kg(N)·hm-2·a-1]下增温分别对0～10 cm和10～20 cm土壤硝化潜势(PNR)、AOA和AOB丰度的影响进行了研究。硝态氮(NO3--N和铵态氮(NH4+-N)含量用分光光度法测量,应用缓冲液培养法测定土壤PNR,提取土壤DNA后用实时荧光定量PCR技术测定功能基因AOA和AOB的丰度。结果表明:温度升高显著增加N1条件下PNR和NO3--N含量(P0.05),降低了N0条件下PNR和NO3--N含量,但差异不显著。N1条件下,增温土壤AOB丰度显著提高(P0.05); N0条件下,增温土壤AOA丰度显著降低(P0.05)。与N0相比, N1条件下的AOA/AOB比值明显降低,表明增温加氮肥处理对AOB的生长刺激更强烈。在增温加施氮条件下,细菌(AOB)表现显著的正反应,在增温不施氮条件下,古菌(AOA)和AOB表现显著的负反应。本研究结果可为全球增温背景下进一步了解硝化活性和氨氧化微生物对增温和氮有效性的响应提供科学依据。     

不同经营强度下毛竹丛枝菌根共生体对氨氧化微生物的影响

利用原位微宇宙试验将丛枝菌根(Arbuscular mycorrhiza,AM)真菌菌丝与根系区分,设置菌根室(RA)和菌丝室(AH)两个分室处理,以粗放经营(extensive management,EM)毛竹林为对照,研究集约经营(Intensive management,IM)条件下毛竹林土壤丛枝菌根共生体对氨氧化微生物群落的影响及其响应机理。结果表明,无论集约经营还是粗放经营AH处理土壤pH均显著降低,且集约经营毛竹林AH处理土壤碱解氮显著降低;不同分室处理对硝化势没有显著影响,但集约经营毛竹林RA处理土壤硝化势显著高于粗放经营;集约经营之后氨氧化古菌(Ammonia-oxidizing archaea,AOA)基因丰度显著降低,而氨氧化细菌(Ammonia-oxidizing bacteria,AOB)基因丰度则在两种经营强度的AH处理中显著降低。不同经营强度和分室处理并未对氨氧化微生物群落组成结构产生显著影响,但网络分析显示集约经营毛竹林氨氧化微生物之间的互作和共生关系优于粗放经营,粗放经营毛竹林氨氧化微生物之间的竞争更为激烈。研究结果为更好地理解毛竹林AM真菌与氨氧化微生物之间的互作关系提供了理论基础。     

水热对三峡水库消落带退耕稻田土壤有机碳矿化的影响

采用模拟培养的方法,研究了不同水热条件对三峡水库消落带退耕稻田土壤有机碳(SOC)矿化的影响。试验共设3个培养温度(10、20和30℃)和4个水分梯度(40%田间持水量(WHC)、70%WHC、100%WHC和浅层淹水)。结果表明:1在66天培养期内,各培养温度(10~30℃)下,70%WHC、100%WHC和浅层淹水处理之间的SOC累积矿化量均无明显差异,其中10℃培养时40%WHC处理下的累积矿化量要显著低于70%WHC和100%WHC水分处理(P0.05),但与浅层淹水无明显差异,而20℃和30℃培养时40%WHC处理下的累积矿化量则要显著低于其他水分处理,表明相较于70%WHC的水分处理,40%WHC水分处理会抑制消落带退耕稻田SOC矿化,而高水分(100%WHC和浅层淹水)对SOC矿化则无明显促进和抑制作用。2在相同水分条件下,消落带退耕稻田SOC累积矿化量均随培养温度升高而增加。3高温下各水分处理之间的温度敏感性无显著差异,而低温下水分对温度敏感性有显著影响,低温浅层淹水处理下的Q10为2.33,显著高于40%WHC处理,与70%WHC和100%WHC处理之间无明显差异。且随着温度升高,浅层淹水下消落带退耕稻田SOC矿化的温度敏感性显著降低,而在土壤含水量≤100%WHC下则无明显变化。温度和水分均能显著影响SOC矿化,但二者无明显的交互效应。4双库一级矿化动力学模型拟合结果表明,水分和温度通过影响消落带退耕稻田土壤易分解有机碳含量和难分解有机碳的矿化速率,从而影响SOC矿化。     

长期施用含氯化肥对棕壤硝化作用及氨氧化微生物的影响

【目的】氨氧化微生物是氨氧化过程的主要驱动者,氨氧化过程作为硝化作用的限速步骤对氮循环具有重要作用。本研究以沈阳农业大学棕壤含氯化肥长期定位试验的土壤为研究对象,探讨了连续34年施用高氯和低氯化肥对棕壤硝化作用及氨氧化微生物的影响。【方法】该长期试验在等量氮、磷、钾条件下,设置高氯和低氯处理,共8个处理:T1(不施肥);T2(单施尿素);T3(尿素+氯化钾);T4(尿素+过磷酸钙);T5(尿素+过磷酸钙+氯化钾);T6(尿素+磷酸一铵+氯化钾);T7(尿素+氯磷铵+氯化钾);T8(硝酸磷肥+过磷酸钙+氯化钾),T7为高氯处理。采集0—20cm土壤样品,利用荧光定量PCR技术测定氨氧化细菌(AOB)和古菌(AOA)丰度,并结合土壤硝化潜势和基本化学性质,分析长期施用含氯化肥对棕壤硝化作用及氨氧化微生物丰度的影响及影响氨氧化微生物丰度的主要环境因素。【结果】长期施肥降低了土壤pH值,高氯处理降低得最多,显著低于其他处理;高氯处理的土壤硝化潜势也显著低于其他处理,且除高氯处理外,配施磷肥的处理土壤硝化潜势显著高于不施磷处理。各处理土壤中AOA丰度均显著高于AOB,高氯处理土壤中AOA、AOB丰度均显著低于其他处理,土壤硝化潜势与AOA和AOB均呈显著正相关关系。【结论】连续施用高氯化肥34年显著降低了棕壤AOA和AOB丰度,抑制了硝化潜势。该结果可为通过含氯化肥的合理施用来调节土壤AOA和AOB,进而调控土壤氮素循环提供参考。     

The role of ammonium oxidizing communities in mediating effects of an invasive plant on soil nitrification

Invasive plants often benefit from changes that they impose on soil microbes via positive plant–soil feedback, but the mechanisms that underlie these changes, and the legacy of their effects, remain poorly quantified. We investigated the impacts of an invasive annual grass, Microstegium vimineum, on the structure and functioning of soil microbial communities in a multi-year, field-based common garden experiment. Given previous reports that M. vimineum can both elevate nitrification rates in soil and benefit from enhanced nitrate availability, we sought to answer the following questions: 1) Does M. vimineum alter the abundance or composition of soil nitrifying microbial communities (ammonia oxidizing archaea and bacteria, AOA and AOB, respectively)? 2) Are such effects reversible or do soil legacy effects persist after M. vimineum is no longer present? After three years, invaded plots had greater AOA abundances than uninvaded native dominated plots, as well as different AOA community structure. However, after seven years, and following a period of M. vimineum replacement by native plants in the invaded plots, AOA abundances and nitrification rates declined toward levels found in uninvaded plots. Collectively, our results suggest that while the impacts of M. vimineum invasions on nitrogen cycling likely relate to their association with AOA, these effects may not persist if M. vimineum declines over time and native plants and their associated microbes are able to re-establish.     

Effects of inorganic fertilizer and manure on soil archaeal abundance at two experimental farms during three consecutive rotation-cropping seasons

Soil archaeal population dynamics at two experimental sites of the same clay-loam type in Ottawa and Woodslee, Ontario, were investigated to determine fertilizer and manure effects following their different long-term crop rotation and fertilization schemes. Phylogenetic analysis of cloned soil archaeal 16S rRNA gene libraries of both sites identified them with group 1.1b of Thaumarchaeota. The gene population dynamics subtly varied in the order of 10⁷ copies g⁻¹ soil when monitored by quantitative real-time PCR during three growing seasons (2007–2009). In Ottawa, where plots were amended with dairy-farm manure, soil thaumarchaeal gene abundance was double of the unamended plots. At the Woodslee N-P-K-fertilized plots, it remained at least 30% fewer than that of the unfertilized ones. These cultivated plots showed soil carbon limitation while the fertilized ones were low in soil pH (ca. 5.5). Surface soils from an unfertilized sod plot and an adjacent deciduous forest had higher total carbon content (C:N ratio of 9 and 11, respectively). Their thaumarchaeal gene abundance varied up to 4.8 × 10⁷ and 7.0 × 10⁷ copies g⁻¹ soil, respectively. The former value was also attained at the manure-amended plots in Ottawa, where the C:N ratio was just below 10. Where soil pH was above 6.0, there was a weak and positive correlation between soil total C and the estimated gene abundance. Such gene population dynamics consistently demonstrated the stimulating and suppressive effects of dairy-farm manure (Ottawa site) and inorganic fertilizers (Woodslee site), respectively, on soil thaumarchaea. At both sites archaeal amoA and 16S rRNA gene abundance were similarly affected. Archaeal amoA gene abundance also outnumbered bacterial amoA abundance, suggesting that ammonia-oxidizing archaea might be dominant in these soils. Only minor crop effects on gene population dynamics were detected.     

青藏高原三种典型生境中硝化微生物分布和群落结构

以青藏高原3种典型生境(荒漠草地、湿地和盐碱地)为研究对象，通过amoA功能基因qPCR和16SrRNA基因扩增子测序，研究了其氨氧化古菌(ammonia-oxidizingarchaea,AOA)、氨氧化细菌(ammonia-oxidizingbacteria,AOB)、亚硝酸盐氧化菌(nitrite-oxidizing bacteria,NOB)和完全硝化细菌(complete ammonia oxidizer,CMX)的分布与群落结构特征。qPCR结果表明，荒漠草地和盐碱地中3种氨氧化微生物，其丰度顺序为AOA>CMX>AOB，而在湿地中则为CMX≥AOA>AOB。各生境中AOA主要类群为土壤类群(即group 1.1b)，且其中约半数属于Nitrosocosmicus属分支，该分支在北极冻土中也有分布。荒漠草地和湿地中AOB主要为亚硝化螺菌属(Nitrosospira spp.,71.21%～100%)，而盐碱地主要为亚硝化单胞菌属(Nitrosomonas spp.,75.51%～88.71%)。3种生境中NOB主要类群均为硝化螺菌属(Nitrospira ...     

Ammonia oxidizer abundance in paddy soil profile with different fertilizer regimes

Studies about ammonia-oxidizing bacteria (AOB) and archaea (AOA) are often focused on topsoil, but little is known about their activity and distribution in subsoil. A long-term fertilizer experiment was conducted to assess the effects of different fertilizer treatments on AOB and AOA in vertical soil profiles of paddy soil plots that received no nitrogen fertilizer control (CK), NPK chemical fertilizers (CF), organic–inorganic mixed fertilizer (OIMF) and organic fertilizer (OF). Soil properties, potential nitrification rate (PNR) and amoA gene abundance of AOB and AOA were measured and analyzed by two-way ANOVA and correlation analysis. Quantitative PCR analysis of amoA genes showed that AOA were more abundant than AOB in all the soil samples. AOB declined sharply with soil depth. Compared with CK and OF treatments, CF and OIMF treatments had higher abundance of AOB throughout the soil profiles. However, AOA tend less responsive to soil depth and fertilizers compared to AOB. This caused the AOA/AOB ratios in subsoil higher than in topsoil, and in CK and OF higher than in CF and OIMF treatments. These results suggest that AOA are more abundant and can be better adapted to nutrient-poor subsoils than AOB, and autotrophic nitrification could likely be determined by a complex suite of environmental factors in vertical profiles of the paddy soil tested.     

pH regulates key players of nitrification in paddy soils

Increasing lines of evidence have suggested the functional importance of ammonia-oxidizing archaea (AOA) rather than bacteria (AOB) for nitrification in upland soils with low pH. However, it remains unclear whether niche specialization of AOA and AOB occurs in rice paddy wetlands constrained by oxygen availability. Using DNA-based stable isotope probing, we conclude that AOA dominated nitrification activity in acidic paddy soils (pH 5.6) while AOB dominated in alkaline soils (pH 8.2). Nitrification activity was stimulated by urea fertilization and accompanied by a significant increase of AOA in acid soils and AOB in alkaline soils. DNA-based stable isotope probing indicated significant assimilation of ¹³CO₂ for AOA only in acidic paddy soil, while AOB was the solely responsible for ammonia oxidation in the alkaline paddy soil. Phylogenetic analysis further indicated that AOA members within the soil group 1.1b lineage dominated nitrification in acid soils. Ammonia oxidation in the alkaline soil was catalyzed by Nitrosospira cluster 3-like AOB, suggesting that the physiological diversity of AOA is more complicated than previously thought, and soil pH plays important roles in shaping the community structures of ammonia oxidizers in paddy field.     

长期施肥对水稻土剖面氨氧化古菌和细菌丰度及组成的影响

长期施肥影响稻田土壤理化性质和硝化微生物群落,但长期施肥对稻田不同土层氨氧化古菌(AOA)和氨氧化细菌(AOB)群落结构的影响尚不明确.以湖南宁乡稻田不同施肥制度长期定位试验为平台,选取不施肥(CK)、施秸秆有机肥(ST)、有机-无机肥配施(OM)和施全量化肥(NPK)4个处理,采用实时荧光定量PCR和Illumina...     

红壤稻田不同生育期土壤氨氧化微生物群落结构

以福建省红壤稻田土壤为对象,通过提取土壤总DNA,利用特异引物进行PCR(聚合酶链反应)扩增和DGGE(变性梯度凝胶电泳)并结合DNA克隆测序,研究了水稻生长过程中稻田土壤氨氧化细菌和氨氧化古菌群落结构的变化。结果显示:稻田土壤具有丰富的氨氧化细菌和氨氧化古菌资源。水稻生长过程中土壤氨氧化细菌群落组成较为稳定,只表现出水稻生长前期(苗期、分蘖期)和中后期(孕穗期、成熟期)间存在一定差异。而土壤氨氧化古菌群落组成变化较大,在水稻生长的苗期、分蘖期、孕穗期和成熟期4个时期间均存在一定差异。在水稻生长过程中,土壤氨氧化细菌群落多样性指数无显著性变化,但氨氧化古菌群落多样性指数随水稻生长明显提高,孕穗期后才达到平稳。水稻生长前期土壤硝化势也具有显著上升趋势,孕穗期时达到最高,而后有所下降。土壤硝化势与氨氧化古菌群落多样性指数具有显著正相关性,与氨氧化细菌没有相关性。研究表明,氨氧化古菌对红壤稻田土壤硝化作用的影响程度较大,证实了氨氧化微生物尤其是氨氧化古菌在稻田土壤微生物组成及其生态系统功能中的重要性。     

Long-term fertilization effects on active ammonia oxidizers in an acidic upland soil in China

The effects of long-term fertilization of acidic soils on ammonia-oxidizing archaea (AOA) and bacteria (AOB) communities and its ecological implications remain poorly understood. We chose an acidic upland soil site under long-term (27-year) fertilization to investigate ammonia oxidizer communities under four different regimes: mineral N fertilizer (N), mineral NPK fertilizer (NPK), organic manure (OM) and an unfertilized control (CK). Soil net nitrification rates were significantly higher in OM soils than in CK, N or NPK soils. Quantitative analysis of the distribution of amoA genes by DNA-based stable isotope probing revealed that AOA dominate in CK, N and NPK soils, while AOB dominate in OM soils. Denaturing gradient gel electrophoresis and clone library analyses of amoA genes revealed that Group 1.1a-associated AOA (also referred to as Nitrosotalea) were the most dominant active AOA population (>92%), while Nitrosospira Cluster 3 and Cluster 9 were predominant among active AOB communities. The functional diversity of active ammonia oxidizers in acidic soils is affected by long-term fertilization practices, and the responses of active ammonia oxidizers to mineral fertilizer and organic manure are clearly different. Our results provide strong evidence that AOA are more highly adapted to growth at low pH and low substrate availability than AOB, and they suggest that the niche differentiation and metabolic diversity of ammonia oxidizers in acidic soils are more complex than previously thought.     

冬种绿肥对水稻土硝化作用的影响

冬闲田种植绿肥是传统的水稻土培肥增产措施,但绿肥-水稻种植系统中,不同绿肥种类对硝化作用的影响规律及调控机制尚不明确.采用盆栽试验,研究了冬种紫云英、油菜、黑麦草对土壤性状及硝化作用的影响,并通过特异性细菌抑制剂(卡那霉素和大观霉素)研究了氨氧化细菌(AOB)和氨氧化古菌(AOA)对硝化作用的相对贡献.结果表明,冬种三...     

海水稻根际效应对滨海盐碱地土壤氨氧化微生物的影响

滨海盐碱地的特殊环境严重限制了土壤氮素转化和利用。微生物介导的水稻根际氨氧化过程是盐碱稻田土壤氮循环的关键过程,但限于研究盲点和技术不足,海水稻根际效应对滨海盐碱地土壤氨氧化微生物群落结构的影响仍少有报道。据此,本研究以“海稻86”为研究对象,分别设置低盐浓度(2 g·kg^–1)和高盐浓度(6 g·kg–1)两组处理进行盆栽试验。结果显示：种植海水稻70 d后,高盐和低盐处理根际土壤的pH分别下降了0.82和0.70个单位,土壤有机质(SOM)含量下降了6.41和4.46 g·kg^–1,腐殖质(HU)含量提高了5.76和4.45 g·kg^–1,全氮(TN)含量减少0.46和0.37 g·kg^–1,表明海水稻可通过降低盐碱地土壤pH,加速有机质分解转化,提高土壤氮循环速率。水稻根际作用可显著提高土壤微生物生物量碳(MBC)、微生物生物量氮(MBN)和微生物呼吸强度,并在种植第55天达到最高,在高盐处理中分别达到850.0 mg·kg^–1、72.2 mg·kg^–1