Community Structure of Ammonia-Oxidizing Bacteria under Long-Term Application of Mineral Fertilizer and Organic Manure in a Sandy Loam Soil

The effects of mineral fertilizer (NPK) and organic manure on the community structure of soil ammonia-oxidizing bacteria (AOB) was investigated in a long-term (16-year) fertilizer experiment. The experiment included seven treatments: organic manure, half organic manure N plus half fertilizer N, fertilizer NPK, fertilizer NP, fertilizer NK, fertilizer PK, and the control (without fertilization). N fertilization greatly increased soil nitrification potential, and mineral N fertilizer had a greater impact than organic manure, while N deficiency treatment (PK) had no significant effect. AOB community structure was analyzed by PCR-denaturing gradient gel electrophoresis (PCR-DGGE) of the amoA gene, which encodes the α subunit of ammonia monooxygenase. DGGE profiles showed that the AOB community was more diverse in N-fertilized treatments than in the PK-fertilized treatment or the control, while one dominant band observed in the control could not be detected in any of the fertilized treatments. Phylogenetic analysis showed that the DGGE bands derived from N-fertilized treatments belonged to Nitrosospira cluster 3, indicating that N fertilization resulted in the dominance of Nitrosospira cluster 3 in soil. These results demonstrate that long-term application of N fertilizers could result in increased soil nitrification potential and the AOB community shifts in soil. Our results also showed the different effects of mineral fertilizer N versus organic manure N; the effects of P and K on the soil AOB community; and the importance of balanced fertilization with N, P, and K in promoting nitrification functions in arable soils.     

Quantitative analyses of the abundance and composition of ammonia-oxidizing bacteria and ammonia-oxidizing archaea of a Chinese upland red soil under long-term fertilization practices

The abundance and composition of soil ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) were investigated by using quantitative real-time polymerase chain reaction, cloning and sequencing approaches based on amoA genes. The soil, classified as agri-udic ferrosols with pH (H(2)O) ranging from 3.7 to 6.0, was sampled in summer and winter from long-term field experimental plots which had received 16 years continuous fertilization treatments, including fallow (CK0), control without fertilizers (CK) and those with combinations of fertilizer nitrogen (N), phosphorus (P) and potassium (K): N, NP, NK, PK, NPK and NPK plus organic manure (OM). Population sizes of AOB and AOA changed greatly in response to the different fertilization treatments. The NPK + OM treatment had the highest copy numbers of AOB and AOA amoA genes among the treatments that received mineral fertilizers, whereas the lowest copy numbers were recorded in the N treatment. Ammonia-oxidizing archaea were more abundant than AOB in all the corresponding treatments, with AOA to AOB ratios ranging from 1.02 to 12.36. Significant positive correlations were observed among the population sizes of AOB and AOA, soil pH and potential nitrification rates, indicating that both AOB and AOA played an important role in ammonia oxidation in the soil. Phylogenetic analyses of the amoA gene fragments showed that all AOB sequences from different treatments were affiliated with Nitrosospira or Nitrosospira-like species and grouped into cluster 3, and little difference in AOB community composition was recorded among different treatments. All AOA sequences fell within cluster S (soil origin) and cluster M (marine and sediment origin). Cluster M dominated exclusively in the N, NP, NK and PK treatments, indicating a pronounced difference in the community composition of AOA in response to the long-term fertilization treatments. These findings could be fundamental to improve our understanding of the importance of both AOB and AOA in the cycling of nitrogen and other nutrients in terrestrial ecosystems.     

Abundance and composition of ammonia-oxidizing bacteria and ammonia-oxidizing archaea communities of an alkaline sandy loam

The abundance and composition of soil ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) communities under different long-term (17 years) fertilization practices were investigated using real-time polymerase chain reaction and denaturing gradient gel electrophoresis (DGGE). A sandy loam with pH (H(2)O) ranging from 8.3 to 8.7 was sampled in years 2006 and 2007, including seven fertilization treatments of control without fertilizers (CK), those with combinations of fertilizer nitrogen (N), phosphorus (P) and potassium (K): NP, NK, PK and NPK, half chemical fertilizers NPK plus half organic manure (1/2OMN) and organic manure (OM). The highest bacterial amoA gene copy numbers were found in those treatments receiving N fertilizer. The archaeal amoA gene copy numbers ranging from 1.54 x 10(7) to 4.25 x 10(7) per gram of dry soil were significantly higher than those of bacterial amoA genes, ranging from 1.24 x 10(5) to 2.79 x 10(6) per gram of dry soil, which indicated a potential role of AOA in nitrification. Ammonia-oxidizing bacteria abundance had significant correlations with soil pH and potential nitrification rates. Denaturing gradient gel electrophoresis patterns revealed that the fertilization resulted in an obvious change of the AOB community, while no significant change of the AOA community was observed among different treatments. Phylogenetic analysis showed a dominance of Nitrosospira-like sequences, while three bands were affiliated with the Nitrosomonas genus. All AOA sequences fell within cluster S (soil origin) and cluster M (marine and sediment origin). These results suggest that long-term fertilization had a significant impact on AOB abundance and composition, while minimal on AOA in the alkaline soil.     

不同施肥制度土壤微生物量碳氮变化及细菌群落16S rDNA V3 片段PCR产物的DGGE分析

应用化学分析和变性梯度凝胶电泳（DGGE）技术分离PCR扩增的16S rDNA的方法,研究了不同施肥制度对土壤微生物量碳、氮变化及微生物多样性的影响。结果表明,连续15a长期试验下,土壤微生物量碳（SMB-C）和微生物量氮（SMB-N）的含量大小均为长期撂荒（CK0）土壤高于农田土壤,而在农田土壤中,长期施肥的处理（NPK、NPKM、NPKSt和NPKF）高于长期不施肥处理（CK）,不同的种植制度中,长期复种轮作（NPKF）高于长期复种连作（NPK）;各处理的SMB-C/SOC（土壤有机碳）和SMB-N/TN（全氮）的比值的变化趋势与SMB-C和SMB-N变化一致;从PCR-DGGE分析,长期氮磷钾化肥配施有机肥（NPKM）处理的微生物量碳、氮的含量最高,微生物丰度最高,细菌物种最多,其次为长期撂荒（CK0）,CK处理细菌物种最少。UPGMC聚类分析表明NPK和NPKF处理细菌的群落结构相似,CK和CK0处理细菌的群落结构相似,而NPKM和NPKSt处理细菌的群落结构相似。     

Impacts of organic and inorganic fertilizers on nitrification in a cold climate soil are linked to the bacterial ammonia oxidizer community

The microbiology underpinning soil nitrogen cycling in northeast China remains poorly understood. These agricultural systems are typified by widely contrasting temperature, ranging from −40 to 38°C. In a long-term site in this region, the impacts of mineral and organic fertilizer amendments on potential nitrification rate (PNR) were determined. PNR was found to be suppressed by long-term mineral fertilizer treatment but enhanced by manure treatment. The abundance and structure of ammonia-oxidizing bacterial (AOB) and archaeal (AOA) communities were assessed using quantitative polymerase chain reaction and denaturing gradient gel electrophoresis techniques. The abundance of AOA was reduced by all fertilizer treatments, while the opposite response was measured for AOB, leading to a six- to 60-fold reduction in AOA/AOB ratio. The community structure of AOA exhibited little variation across fertilization treatments, whereas the structure of the AOB community was highly responsive. PNR was correlated with community structure of AOB rather than that of AOA. Variation in the community structure of AOB was linked to soil pH, total carbon, and nitrogen contents induced by different long-term fertilization regimes. The results suggest that manure amendment establishes conditions which select for an AOB community type which recovers mineral fertilizer-suppressed soil nitrification.     

施肥方式对干旱半干旱地区土壤氨氧化微生物数量和群落的影响

氨氧化是硝化作用的限速步骤,也是评估土壤氮循环和提高氮肥利用效率的重要指标。以内蒙古农牧业科学院旱作实验站长期定位实验为基础,通过实时荧光定量PCR和末端限制性片段长度多态性分析,研究了5种施肥方式（单施氮肥、单施有机肥、氮磷钾配施、有机无机配施和不施肥）对土壤氨氧化古菌（AOA）和氨氧化细菌（AOB）群落丰度、结构和活性的影响。结果表明：单施氮肥、氮磷钾肥配施以及有机无机肥配施均能显著提高AOB的丰度以及土壤硝化潜势。Nitrosospiria cluster 3a.1是不施肥土壤中主要的AOB种群,而施用氮肥后优势种群转变为Nitrosospiria cluster 3a.2。Nitrosospiria cluster 3b的比例在施用有机肥处理土壤中显著升高。在干旱半干旱地区,土壤pH和含水量是解释AOB群落结构变化的关键环境因子。AOA的丰度在单独施用氮肥处理中显著升高,但不同施肥方式对AOA的群落结构没有显著影响。     

长期施肥对华北典型潮土N分配和N2O排放的影响

利用长期定位肥料试验研究化学肥料N、有机肥料N以及化学肥料N和有机肥料N混合施用对N分配和N2O排放影响。处理包括化学肥料N、P、K的不同组合NPK、NP、NK、PK、全部施用有机肥料N（OM）、一半化学肥料N＋一半有机肥料N（1／2OM）及不施肥（CK）7个处理。结果表明,等N条件下,处理间N2O排放的差异不显著,N2O排放主要发生在玉米生长期。均衡提供N、P和K显著提高土壤N储量,有机肥料N的效果显著高于化学N肥。施肥也影响N的利用效率和N在作物中的分配。均衡的养分供应有利于N在子粒中积累,而养分缺乏的处理,秸秆中N含量相对较高。进入环境的N量以NK最多,1／20M最少。总体而言,施P肥和有机肥可减少N2O的间接排放,提高土壤N素肥力并能获得较高的产量。     

Arbuscular mycorrhizal fungal community structure and diversity in response to long-term fertilization: a field case from China

The influences of different fertilizer treatments on spore community structure and diversity of arbuscular mycorrhizal (AM) fungi (AMF) were investigated in a long-term fertilization experiment with seven treatments: organic manure (OM), half organic manure N plus half fertilizer N (1/2 OMN), fertilizer NPK, fertilizer NP, fertilizer NK, fertilizer PK, and the control (without fertilization). Fertilization generally increased the nutrient contained in the fertilizer and treatments with NPK and 1/2 OMN produced the highest crop yields. Thirty-five species of AMF within 6 genera, including 8 previously undescribed species, were recovered. Similarly in all seven treatments, the most abundant genus was Glomus, and followed by Acaulospora. All the fertilization treatments changed AM species composition, and NK treatment had the slightest influence. Fertilization with fertilizers NP, PK and NPK markedly increased AM fungal spore density, while 1/2 OMN, OM and NK treatments showed no significant influences. All the fertilizer treatments, especially OM, significantly decreased species richness and species diversity (Shannon-Weiner index). There were no significant correlations between AM fungal parameters (spore density, species richness and species diversity) and soil properties. The findings indicate that long-term fertilization all can change AM fungal community structure and decrease species diversity, while balanced fertilization with NPK or 1/2 OMN is the most suitable fertilization regime if taking both crop yields and AM species diversity into account.     

Does long-term fertilization treatment affect the response of soil ammonia-oxidizing bacterial communities to Zn contamination?

Experiments were conducted to examine the effects of long-term fertilization and acute Zn toxicity on the size, nitrification activity and community structure of autotrophic ammonia-oxidizing populations of the β-subgroup of the class Proteobacteria in arable soils. Plots under different long-term fertilization regimes were sampled, and then different concentrations of ZnCl₂ were spiked into soil samples for 8 weeks. It was found that long-term fertilization significantly increased nitrification rates and population size, and there was a positive correlation between them. A shift in the composition of AOB was also detected in samples fertilized with mineral N fertilizer (NPK) and organic matter (OM) as compared to unfertilized sample. EC50 values suggested that there was no significant difference in Zn toxicity to nitrification rates among the three fertilization treatments. Long-term fertilization did not improve the resilience of AOB activity to Zn toxicity.     

施肥和土壤管理对土壤微生物生物量碳、氮和群落结构的影响

以中国科学院沈阳生态试验站的长期定位试验为平台,研究了不同施肥和土壤管理对潮棕壤微生物生物量碳、氮和群落结构的影响。结果表明,裸地和农田处理的微生物生物量碳、氮较低,但是农田处理下施肥增加了微生物生物量,其中NPK+M效果最明显。DGGE图谱显示,处理间细菌条带分布较相似,其中裸地的细菌多样性最高;长期施肥和土壤管理改变了土壤真菌群落结构,施肥增加了真菌多样性,且有机肥的影响大于化肥;不同处理间氨氧化细菌群落结构差异显著,NPK+M显著增加了氨氧化细菌多样性,且无机肥和有机肥对氨氧化细菌群落影响不同。施肥和土壤管理对细菌影响较小,但显著改变了真菌和氨氧化细菌的群落结构。聚类分析结果显示,土壤管理措施较施肥对细菌、真菌和氨氧化细菌群落的影响更为显著。     

长期不同施肥制度对水稻土氨氧化微生物数量和群落结构的影响

由氨氧化微生物驱动的氨氧化过程是硝化作用的限速步骤,在土壤氮素循环过程中扮演着重要角色.以湖南省宁乡县长达30 a定位试验水稻土壤为研究对象,采用荧光定量PCR和Illumina MiSeq高通量测序分析方法,以amoA基因为靶标,研究了4种施肥制度[不施肥(CK)、化肥(CF)、70%化肥+30%有机肥(CFM₁)和40%化肥+60%有机肥(CFM₂)]水稻土壤氨氧化微生物的数量和群落结构变化.结果表明: 不同施肥处理氨氧化古菌(AOA)和氨氧化细菌(AOB) amoA基因拷贝数分别为3.09×10⁷～8.37×10⁷和1.04×10⁷～7.03×10⁷ copies·g^-1干土.施肥显著提高了AOA和AOB数量,但处理CFM₂中AOB数量与CK差异不显著.有机肥配施比例对AOB群落α多样性指数的影响强于AOA,处理CFM₁中AOA群落的多样性指数(Shannon)和AOB群落的丰富度指数(ACE和Chao1)均显著高于CK.奇古菌门和泉古菌门是AOA群落的优势门类群,占AOA amoA基因总序列的83.4%;亚硝化螺菌属、environmental_samples_norank、Bacteria_unclassified和Nitrosomonadales_unclassified是AOB群落的优势属类群,占AOB amoA基因总序列的97.8%.维恩分析结果显示,有机肥配施比例对AOB群落操作分类单元(OTU)数量的影响强于AOA,但对各处理共有AOA和AOB amoA基因序列条数的影响均较小.冗余分析结果显示,不同施肥处理AOB群落结构差异强于AOA,且所有土壤理化性质均与AOA和AOB群落结构存在显著相关关系.综上可知:有机肥配施比例显著改变了AOA和AOB数量、多样性和群落结构,配施30%有机肥时,AOA群落的Shannon指数最高,AOB群落数量、ACE和Chao1指数均最高.研究结果可为进一步探讨农业系统中氨氧化微生物对不同施肥制度的响应机制及其在氮素转化中的作用提供科学依据.     

秸秆还田对玉米根际氨氧化微生物群落及红壤硝化潜势的影响

为探讨酸性红壤根际氨氧化微生物群落以及硝化作用对不同秸秆还田处理的响应,基于中国科学院鹰潭红壤生态实验站设置的秸秆还田长期试验平台(9年),采用荧光定量PCR和高通量测序技术,研究不同秸秆还田处理(不施肥(CK);氮磷钾肥(NPK);氮磷钾肥+秸秆(NPKS);氮磷钾肥+秸秆猪粪配施(NPKSM);氮磷钾肥+秸秆生物炭(NPKB))下玉米根际土壤氨氧化古菌(ammonia-oxidizing archaea, AOA)和细菌(ammonia-oxidizing bacteria, AOB)丰度和群落结构的变化,揭示了秸秆还田对根际氨氧化微生物群落结构和硝化潜势(potential nitrification activity, PNA)的影响机制。结果发现：相比CK和NPK处理,秸秆还田显著提高了土壤养分含量和硝化潜势,其中有机碳(SOC)、全氮(TN)、全磷(TP)、速效磷(AP)、速效钾(AK)、硝态氮(NO~-₃-N)和铵态氮(NH~+₄-N)含量显著增加,NPKSM处理对土壤肥力提升效果最佳。AOA的硝化潜势显著高于AOB,表明AOA...     

Fertilization regimes affect the soil biological characteristics of a sudangrass and ryegrass rotation system

The sudangrass (Sorghum sudanense) and ryegrass (Lolium multiflorum L.) rotation is an intensive and new cropping system in Central China. Nutrient management practices in this rotation system may influence soil fertility, the important aspects of which are soil biological properties and quality. As sensitive soil biological properties and quality indicators, soil microbial community activity, microbial biomass, enzyme activities, soil organic matter (SOM) and total N resulting from different fertilization regimes in this rotation system were studied through a four-year field experiment from April 2005 to May 2009. Treatments included control (CK), fertilizer phosphorus and potassium (PK), fertilizer nitrogen and potassium (NK), fertilizer nitrogen and phosphorus (NP) and a fertilizer nitrogen, phosphorus and potassium combination (NPK). Soil microbial community activities in the NK, NP and NPK treatments were significantly lower than those in the CK and PK treatments after the sudangrass and ryegrass trial. The highest microbial biomass C, microbial biomass N, SOM, total N, sucrase and urease activities were found in the NPK treatment, and these soil quality indicators were significantly higher in the NK, NP and NPK treatments than in the PK and CK treatments. Soil microbial biomass and enzyme activities were positively associated with SOM in the sudangrass and ryegrass rotation system, indicating that fertilization regimes, especially N application, reduced microbial community activity in the soil. Proper fertilization regimes will increase microbial biomass, enzyme activity and SOM and improve soil fertility.     

长期施肥对土壤氨氧化微生物的影响

长期施肥可改变土壤碳氮等养分供应,进而影响微生物数量与群落组成。本研究基于棕壤长期定位实验站,分析不同施肥方式下(不施肥,CK;低量无机氮肥,N₂;高量无机氮肥,N₄;有机无机氮肥配施,M₂N₂)土壤氨氧化古菌(AOA)和细菌(AOB)的变化,为土壤氮素转化的微生物学机制和培肥土壤提供依据。结果表明:不同施肥方式下,土壤AOA与AOB的数量比值为2.28～61.95。与CK相比,施肥后土壤AOA数量降低了1.6%～13.6%。N₄处理AOB数量随土壤深度增加呈先降低后升高的趋势,其他处理则相反。土壤AOB群落Shannon多样性指数、均匀度指数和Simpson指数均高于AOA。M₂N₂处理0～20 cm土层土壤AOB多样性增加,但AOA多样性降低。土壤AOB主要因土壤深度发生聚类,AOB和AOA均未因施肥方式发生聚类。综上,长期施肥改变了土壤AOA和AOB的构成状况,AOA对环境变化较为敏感,AOB较为丰富和稳定。     

The effects of mineral fertilizer and organic manure on soil microbial community and diversity

The effects of mineral fertilizer (NPK) and organic manure on phospholipid fatty acid profiles and microbial functional diversity were investigated in a long-term (21-year) fertilizer experiment. The experiment included nine treatments: organic manure (OM), organic manure plus fertilizer NPK (OM + NPK), fertilizer NPK (NPK), fertilizer NP (NP), fertilizer NK (NK), fertilizer N (N), fertilizer P (P), fertilizer K (K), and the control (CK, without fertilization). The original soil was extremely eroded, characterized by low pH and deficiencies of nutrients, particularly N and P. The application of OM and OM + NPK greatly increased crop yields, soil pH, organic C, total N, P and K, available N, P and K content. Crop yields, soil pH, organic C, total N and available N were also clearly increased by the application of mineral NPK fertilizer. The amounts of total PLFAs, bacterial, Gram-negative and actinobacterial PLFAs were highest in the OM + NPK treatment, followed by the OM treatment, whilst least in the N treatment. The amounts of Gram-positive and anaerobic PLFAs were highest in the OM treatment whilst least in the P treatment and the control, respectively. The amounts of aerobic and fungal PLFAs were highest in the NPK treatment whilst least in the N and P treatment, respectively. The average well color development (AWCD) was significantly increased by the application of OM and OM + NPK, and the functional diversity indices including Shannon index (H ^′ ), Simpson index (D) and McIntosh index (U) were also significantly increased by the application of OM and OM + NPK. Principal component analysis (PCA) of PLFA profiles and C source utilization patterns were used to describe changes in microbial biomass and metabolic fingerprints from nine fertilizer treatments. The PLFA profiles from OM, OM + NPK, NP and NPK were significantly different from that of CK, N, P, K and NK, and C source utilization patterns from OM and OM + NPK were clearly different from organic manure deficient treatments (CK, N, P, K, NP, NK 6 and NPK). Stepwise multiple regression analysis showed that total N, available P and soil pH significantly affected PLFA profiles and microbial functional diversity. Our results could provide a better understanding of the importance of organic manure plus balanced fertilization with N, P and K in promoting the soil microbial biomass, activity and diversity and thus enhancing crop growth and production.     

长期施肥对黄淮海平原农田中小型土壤节肢动物的影响

在2008年9月和2009年2月,采用改良干漏斗方法(Modified Tullgren)对黄淮海地区长期定位施肥试验下中小型土壤节肢动物进行调查。试验包括氮磷钾(NPK)、氮磷(NP)、氮钾(NK)、磷钾(PK)、有机肥(OM)、1∶1化学氮肥与有机氮肥(OMNPK)和不施肥(CK)7个处理。结果表明:OM和OMNPK处理有利于提高土壤动物丰富度和多样性;NK处理不利于土壤动物的生存和发展,缺磷影响了土壤动物数量的增长;从优势类群弹尾目和蜱螨目来看,OM和OMNPK处理对弹尾目等节跳科、棘跳科和球角跳科的生长有利,而圆跳科在NPK处理下具有更高的数量;OMNPK处理对蜱螨目中气门亚目有显著的正效应,对前气门亚目和甲螨亚目也有一定的正向作用;氮肥对弹尾目没有表现出正相关关系,但在一定程度上增加了蜱螨目的数量。     

Effects of temperature and fertilizer on activity and community structure of soil ammonia oxidizers

We investigated the effect of temperature on the activity of soil ammonia oxidizers caused by changes in the availability of ammonium and in the microbial community structure. Both short (5 days) and long (6.5, 16 and 20 weeks) incubation of an agricultural soil resulted in a decrease in ammonium concentration that was more pronounced at temperatures between 10 and 25 degrees C than at either 4 degrees C or 30-37 degrees C. Consistently, potential nitrification was higher between 10 and 25 degrees C than at either 4 degrees C or 37 degrees C. However, as long as ammonium was not limiting, release rates of N2O increased monotonously between 4 and 37 degrees C after short-term temperature adaptation, with nitrification accounting for about 35-50% of the N2O production between 4 and 25 degrees C. In order to see whether temperature may also affect the community structure of ammonia oxidizers, we studied moist soil during long incubation at low and high concentrations of commercial fertilizer. The soil was also incubated in buffered (pH 7) slurry amended with urea. Communities of ammonia oxidizers were assayed by denaturant gradient gel electrophoresis (DGGE) of the amoA gene coding for the alpha subunit of ammonia monooxygenase. We found that a polymerase chain reaction (PCR) system using a non-degenerated reverse primer (amoAR1) gave the best results. Community shifts occurred in all soil treatments after 16 weeks of incubation. The community shifts were obviously influenced by the different fertilizer treatments, indicating that ammonium was a selective factor for different ammonia oxidizer populations. Temperature was also a selective factor, in particular as community shifts were also observed in the soil slurries, in which ammonium concentrations and pH were better controlled. Cloning and sequencing of selected DGGE bands indicated that amoA sequences belonging to Nitrosospira cluster 1 were dominant at low temperatures (4-10 degrees C), but were absent after long incubation at low fertilizer treatment. Sequences of Nitrosospira cluster 9 could only be detected at low ammonium concentrations, whereas those of Nitrosospira cluster 3 were found at most ammonium concentrations and temperatures, although individual clones of this cluster exhibited trends with temperature. Obviously, ammonia oxidizers are able to adapt to soil conditions by changes in the community structure if sufficient time (several weeks) is available.     

黄壤稻田土壤微生物生物量碳磷对长期不同施肥的响应

本研究以进行了22年的黄壤稻田长期定位试验为依托,分析了不同施肥模式下土壤碳(C)、磷(P)与微生物生物量C(MBC)、P(MBP)的变化及其耦合特征,旨在探讨黄壤地区合理培肥模式以提高土壤磷素有效性.试验包括10个处理,分别为不施肥(CK)、单施氮肥(N)、磷钾配合(PK)、氮钾配合(NK)、氮磷配合(NP)、氮磷钾配合(NPK)、单施有机肥(M)、3种有机无机肥配施(1/4M+3/4NP、0.5MNP、MNPK).结果表明:与不施肥相比,N和NK处理土壤有机碳(TOC)、全磷(TP)、MBC、MBP均有不同程度的降低,施磷处理(PK、NP、NPK)则有不同程度的提升;与不施肥和施用无机肥相比,施用有机肥各处理TOC、MBC、MBP及MBP/TP均显著增加,其中M和MNPK处理增幅最大.MBC/MBP、TOC/MBP、MBC/TP以施用有机肥处理最低,N处理最高.土壤MBC、MBP及其耦合关系与土壤TOC和有效磷均呈极显著相关,TOC是影响MBC、MBP、MBP/TP的直接因素,而有效磷则是影响MBC/MBP、TOC/MBP、MBC/TP的直接因素.土壤MBP及碳、磷耦合关系各指标可以有效区分单施化肥和施用有机肥的不同施肥方式,可作为评价黄壤稻田磷素肥力的生物学指标.配施有机肥是增加黄壤稻田磷有效性、提高土壤供磷潜力和保持土壤生物健康的有效途径.     

长期施肥对新疆灰漠土土壤微生物群落结构与功能多样性的影响

以20a新疆国家灰漠土土壤肥力与肥料效益长期定位试验为平台,采用常规培养法,结合Biolog技术对可培养微生物、生理菌群数量和碳源利用进行测定分析,研究撂荒(CK0)、耕作不施肥(CK)、不同化肥(N、NK、NP、PK、NPK)、化肥配施低量高量有机肥(NPKM1和NPKM2)和秸秆还田(NPKS)等10种处理土壤微生物特征,揭示长期施肥对土壤微生物群落结构与功能多样性的影响。结果表明:(1)可培养微生物:与CK处理相比,CK0处理显著提高了细菌、放线菌和真菌的数量(P0.05),NPKS处理微生物数量则显著降低(P0.05);不同化肥处理的细菌(除PK处理外)、放线菌(除PK和N处理外)数量也有所增加,增幅在8.14%—135.70%和15.30%—44.78%之间;真菌数量(除NK处理外)则有一定幅度的降低;NPKM1和NPKM2处理,微生物数量最高,细菌分别增加了162.20%和173.75%,放线菌增加了34.39%和39.37%,真菌增加了63.33%和488.33%;(2)生理菌群:与CK0相比,CK处理显著提高了自生固氮菌和亚硝化细菌数量(P0.05),显著降低了氨化细菌和纤维素分解菌数量(P0.05);与CK相比,NPKM1和NPKM2处理显著提高土壤中与氮素转化有关的生理菌群数量(P0.05),不同化肥处理和NPKS处理的影响不相同,NPK处理显著高于其余处理(P0.05);(3)微生物碳源利用:微生物活性表现为NK、NPKM1、NPKM2N、NPK、CKPK、NPKSCK0、NP;CK0处理3个多样性指数以及NPKM1、NPKM2和NK处理Shannon(H)指数最高,其余施肥处理差异不显著;糖类、氨基酸类、羧酸类和胺类是微生物利用的主要碳源。(4)聚类分析表明,除NP处理外,施氮处理土壤有较为相似的碳源利用,细菌和真菌与养分之间有较好的相关性,可培养微生物和生理菌群与微生物碳源利用的相关性较差。因此,长期不同施肥对新疆灰漠土土壤微生物群落结构和功能多样性产生了显著的影响,长期耕作不施肥降低了土壤微生物群落结构和功能多样性,不同化肥配合施用对微生物群落的影响不同,NPK及NPK配施有机肥可提高土壤微生物多样性。     

长期施肥对小麦-玉米作物系统土壤颗粒有机碳和氮的影响

通过对华北平原小麦-玉米轮作农田生态系统18年田间施肥试验,研究了长期不同施肥处理对耕层(0～20 cm)土壤颗粒有机碳和氮及矿质结合有机碳和氮的影响.施肥处理包括化肥NPK不同组合（NPK、NP、NK、PK）、全部施用有机肥(OM)、一半有机肥+化肥NPK(1/2OMN)及不施肥(CK)共7个处理.结果表明：各施肥处理均能在不同程度上增加土壤颗粒有机碳和氮及矿质结合有机碳和氮含量,提高土壤颗粒有机碳和氮分配比例及颗粒有机质C/N.施肥处理颗粒有机碳和氮储量较不施肥处理分别增加11.7%～196.8%和13.0%～152.2%,土壤颗粒有机碳对总有机碳储量增加的贡献率为31.5%～67.3%,土壤颗粒有机氮对全氮储量增加的贡献率为14.3%～100.0%;矿质结合有机碳和氮储量较不施肥处理分别增加2.0%～75.0%和0.0%～69.8%.各处理颗粒有机碳和氮及矿质结合有机碳和氮储量均以OM处理最高,且有机肥与化肥NPK配施高于单施化肥各处理,而化肥处理中NPK均衡施用效果最好.说明施用有机肥、有机肥与化肥NPK配施及化肥NPK均衡施用是增加土壤颗粒有机碳和氮及矿质结合有机碳和氮的关键.