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1.
The community structure of methanogenic archaea is relatively stable,i.e.,it is sustained at a high abundance with minimal changes in composition,in paddy field soils irrespective of submergence and drainage.In contrast,the abundance in non-methanogenic oxic soils is much lower than that in paddy field soils.This study aimed to describe methanogenic archaeal community development following the long-term submergence of non-methanogenic oxic upland field soils in pot and field experiments.In the pot experiment,a soil sample obtained from an upland field was incubated under submerged conditions for 275 d.Soil samples periodically collected were subjected to culture-dependent most probable number(MPN)enumeration,polymerase chain reaction-denaturing gradient gel electrophoresis(PCR-DGGE)analysis of archaeal 16 S r RNA gene,and quantitative PCR analysis of the methyl-coenzyme M reductase alpha subunit gene(mcr A)of methanogenic archaea.The abundance of methanogenic archaea increased from 102 to 103 cells g-1 dry soil and 104 to 107 copies of mcr A gene g-1 dry soil after submergence.Although no methanogenic archaeon was detected prior to incubation by the DGGE analysis,members from Methanocellales,Methanosarcinaceae,and Methanosaetaceae proliferated in the soils,and the community structure was relatively stable once established.In the field experiment,the number of viable methanogenic archaea in a rice paddy field converted from meadow(reclaimed paddy field)was monitored by MPN enumeration over five annual cycles of field operations.Viability was also determined simultaneously in a paddy field where the plow layer soil from a farmer’s paddy field was dressed onto the meadow(dressed paddy field)and an upland crop field converted from the meadow(reclaimed upland field).The number of viable methanogenic archaea in the reclaimed paddy field was below the detection limit before the first cultivation of rice and in the reclaimed upland field.Then,the number gradually increased over five years and finally reached 103–104 cells g-1 dry soil,which was comparable to that in the dressed paddy field.These findings showed that the low abundance of autochthonous methanogenic archaea in the non-methanogenic oxic upland field soils steadily proliferated,and the community structure was developed following repeated and long-term submergence.These results suggest that habitats suitable for methanogenic archaea were established in soil following repeated and long-term submergence. 相似文献
2.
Kenna E. REWCASTLE Jessica A. M. MOORE Jeremiah A. HENNING Melanie A. MAYES Courtney M. PATTERSON Gangsheng WANG Daniel B. METCALFE Aim&#;e T. CLASSEN 《土壤圈》2020,30(1):135-145
Northern peatlands store nearly one-third of terrestrial carbon(C)stocks while covering only 3%of the global landmass;nevertheless,the drivers of C cycling in these often-waterlogged ecosystems are different from those that control C dynamics in upland forested soils.To explore how multiple abiotic and biotic characteristics of bogs interact to shape microbial activity in a northern,forested bog,we added a labile C tracer(13C-labeled starch)to in situ peat mesocosms and correlated heterotrophic respiration with natural variation in several microbial predictor variables,such as enzyme activity and microbial biomass,as well as with a suite of abiotic variables and proximity to vascular plants aboveground.We found that peat moisture content was positively correlated with respiration and microbial activity,even when moisture levels exceeded total saturation,suggesting that access to organic matter substrates in drier environments may be limiting for microbial activity.Proximity to black spruce trees decreased total and labile heterotrophic respiration.This negative relationship may reflect the influence of tree evapotranspiration and peat shading effects;i.e.,microbial activity may decline as peat dries and cools near trees.Here,we isolated the response of heterotrophic respiration to explore the variation in,and interactions among,multiple abiotic and biotic drivers that influence microbial activity.This approach allowed us to reveal the relative influence of individual drivers on C respiration in these globally important C sinks. 相似文献
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Xiaojing HU Junjie LIU Dan WEI Ping ZHU Xi'an CUI Baoku ZHOU Xueli CHEN Jian JIN Xiaobing LIU Guanghua WANG 《土壤圈》2020,30(1):73-86
Denitrification is one of the major processes causing nitrogen loss from arable soils.This study aimed to investigate the responses of nir S-type denitrifier communities to different chronic fertilization regimes across the black soil region of Northeast China.Soil samples were collected from sites located in the north(NB),middle(MB),and south(SB)of the black soil region of Northeast China,each with four chronic fertilization regimes:no fertilizer(No F),chemical fertilizer(CF),manure(M),and chemical fertilizer plus manure(CFM).Methods of quantitative polymerase chain reaction(q PCR)and Illumina Mi Seq sequencing were applied to assess the abundance and composition of denitrifier communities by targeting the nir S gene.The results showed that the M and CFM regimes significantly increased the abundances of nir S-type denitrifiers compared with No F at the three locations.The majority of nir S sequences were grouped as unclassified denitrifiers,and the different fertilizers induced little variation in the relative abundance of known nir S-type denitrifier taxa.Over 90%of the sequences were shared among the four fertilization regimes at each location,but none of the abundant operational taxonomic units(OTUs)were shared among the three locations.Principal coordinate analysis(PCo A)revealed that the communities of nir S-type denitrifier were separated into three groups that corresponded with their locations.Although similar fertilization regimes did not induce consistent changes in the nir S-type denitrifier communities,soil p H and NO-3-N content simultaneously and significantly influenced the structure of nir S-type denitrifier communities at the three locations.Our results highlight that geographical separation rather than chronic fertilization was the dominant factor determining the nir S-type denitrifier community structures,and similar chronic fertilization regimes did not induce consistent shifts of nir S-type denitrifier communities in the black soils. 相似文献
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Humic substances acting as an electron shuttle and nitrogen transformation process influence remarkably the electron transfer in anaerobic reaction systems and thus may affect the reductive dechlorination of hexachlorobenzene(HCB). In order to develop an efficient agricultural strategy for the remediation of organochlorine-contaminated soils, a batch incubation experiment was conducted to study the effects of humic acid, urea, and their interaction on the reductive dechlorination of HCB in a Hydragric Acrisol with high iron oxide content. After 44 d of anaerobic incubation, the five treatments, sterile control,control, humic acid, urea, and humic acid + urea decreased HCB residues by 28.8%, 47.8%, 64.7%, 57.8%, and 71.3%, respectively. The amendment of humic acid or urea significantly decreased soil Eh values and accelerated Fe(Ⅲ) reduction to Fe(Ⅱ), thus promoting markedly reductive dechlorination of HCB. Humic acid had a larger dechlorination effect than urea. Since there was a synergistic interaction between humic acid and urea that accelerated HCB dechlorination, the treatment having both amendments together was the most efficient for HCB dechlorination. The results showed that the combination of NH4+-N supplied by a fertilizer and humic substance is a feasible strategy for the remediation of organochlorine-contaminated soils with abundant iron oxide. 相似文献
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Muhammad S. A. KHAN Lynette K. ABBOTT Zakaria M. SOLAIMAN Peter R. MAWSON Ian S. WAITE Sasha N. JENKINS 《土壤圈》2022,32(2):339-347
Excess nitrogen(N) fertiliser use in agriculture is associated with water pollution and greenhouse gas emissions.While practices and programs to reduce N fertiliser application continue to be developed,inefficient fertiliser use persists.Practices that reduce mineral N fertiliser application are needed in a sustainable agricultural ecosystem to control leaching and gaseous losses for environmental management.This study evaluated whether fully or partially replacing mineral N fertiliser with zoo compost(Perth Zoo) could be a good mitigation strategy to reduce mineral N fertiliser application without affecting wheat yield and nutrition.To achieve this,a glasshouse experiment was conducted to assess the complementary effect of zoo compost and mineral N fertiliser on wheat yield and nutrition in a sandy soil of southwestern Australia.Additionally,a chlorophyll meter was used to determine whether there was a correlation between chlorophyll content and soil mineral N content,grain N uptake,and grain protein content at the tillering(42 d after sowing(DAS)) and heading(63 DAS) growth stages.The standard practice for N application for this soil type in this area,100 kg ha-1,was used with a soil bulk density of 1.3 g cm-3 to calculate the amount of mineral N(urea,46% N) and Perth Zoo compost(ZC)(0.69% N) for each treatment.Treatments comprised a control(no nutrients added,T1),mineral N only(100 kg N ha-1,T2),ZC only(100 kg N ha-1,T7),and combinations of mineral N and ZC at different rates(mineral N at 100 kg N ha-1+ ZC at 25 kg N ha-1(T3),mineral N at 75 kg N ha-1+ ZC at 25 kg N ha-1(T4),mineral N at 75 kg N ha-1+ ZC at 50 kg N ha-1(T5),and mineral N at 50 kg N ha-1+ ZC at 50 kg N ha-1(T6)).The T6 treatment significantly increased grain yield(by 26%) relative to the T2 treatment.However,the T7 treatment did not affect grain yield when compared to the T2 treatment.All treatments with mineral N and ZC in combination significantly improved the 1 000-grain weight compared to the T2 treatment.Chlorophyll content was better correlated with soil mineral N content(r = 0.61),grain N uptake(r = 0.62),and grain protein content(r = 0.80) at heading(63 DAS) than at tillering(42 DAS).While ZC alone could not serve as an alternative to mineral N fertiliser,its complementary use could reduce the mineral N fertiliser requirement by up to 50% for wheat without compromising grain yield,which needs to be verified in the field.Chlorophyll content could be used to predict soil mineral N at the heading stage,and further studies are warranted to verify its accuracy in the field.Overall,the application of ZC as part of integrated nutrient management improved crop yield with reduced N fertiliser application. 相似文献
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Zhongjun JIA Xue ZHOU Weiwei XIA Dario FORNARA Baozhan WANG Elizabeth Anne WASSON Peter CHRISTIE Martin F. POLZ David D. MYROLD 《土壤圈》2020,30(1):87-97
Long-term nitrogen(N)fertilization imposes strong selection on nitrifying communities in agricultural soil,but how a progressively changing niche affects potentially active nitrifiers in the field remains poorly understood.Using a 44-year grassland fertilization experiment,we investigated community shifts of active nitrifiers by DNA-based stable isotope probing(SIP)of field soils that received no fertilization(CK),high levels of organic cattle manure(HC),and chemical N fertilization(CF).Incubation of DNA-SIP microcosms showed significant nitrification activities in CF and HC soils,whereas no activity occurred in CK soils.The 44 years of inorganic N fertilization selected only 13C-ammonia-oxidizing bacteria(AOB),whereas cattle slurry applications created a niche in which both ammonia-oxidizing archaea(AOA)and AOB could be actively13C-labeled.Phylogenetic analysis indicated that Nitrosospira sp.62-like AOB dominated inorganically fertilized CF soils,while Nitrosospira sp.41-like AOB were abundant in organically fertilized HC soils.The 13C-AOA in HC soils were affiliated with the 29i4 lineage.The 13C-nitrite-oxidizing bacteria(NOB)were dominated by both Nitrospira-and Nitrobacter-like communities in CF soils,and the latter was overwhelmingly abundant in HC soils.The 13C-labeled nitrifying communities in SIP microcosms of CF and HC soils were largely similar to those predominant under field conditions.These results provide direct evidence for a strong selection of distinctly active nitrifiers after 44 years of different fertilization regimes in the field.Our findings imply that niche differentiation of nitrifying communities could be assessed as a net result of microbial adaption over 44 years to inorganic and organic N fertilization in the field,where distinct nitrifiers have been shaped by intensified anthropogenic N input. 相似文献
7.
Functional redundancy in soil microbial communities seems to contradict the notion that individual species have distinct metabolic niches in multi-species communities.All soil microbiota have the metabolic capacity for"basic"functions(e.g.,respiration and nitrogen and phosphorus cycling),but only a few soil microbiota participate in"rare"functions(e.g.,methanogenesis and mineralization of recalcitrant organic pollutants).The objective of this perspective paper is to use the phylogenetic niche conservatism theory as an explanation for the functional redundancy of soil microbiota.Phylogenetic niche conservatism is defined as the tendency for lineages to retain ancestral functional characteristics through evolutionary time-scales.The present-day soil microbiota is the result of a community assembly process that started when prokaryotes first appeared on Earth.For billions of years,microbiota have retained a highly conserved set of core genes that control the essential redox and biogeochemical reactions for life on Earth.These genes are passed from microbe to microbe,which contributes to functional redundancy in soil microbiota at the planetary scale.The assembly of microbial communities during soil formation is consistent with phylogenetic niche conservatism.Within a specific soil,the heterogeneous matrix provides an infinite number of sets of diverse environmental conditions,i.e.,niches that lead to the divergence of microbial species.The phylogenetic niche conservatism theory predicts that two or more microbial species diverging from the same clade will have an overlap in their niches,implying that they are functionally redundant in some of their metabolic processes.The endogenous genetic factors that constrain the adaptation of individuals and,thus,populations to changing environmental conditions constitute the core process of phylogenetic niche conservatism.Furthermore,the degree of functional redundancy in a particular soil is proportional to the complexity of the considered function.We conclude with a conceptual model that identifies six patterns of functional redundancy in soil microbial communities,consistent with the phylogenetic niche conservatism theory. 相似文献
8.
In rice-wheat rotation systems, changes in soil phosphorus(P) pools and microorganisms in rice-growing seasons have been studied;however, further investigations are required to test whether these indexes exhibit different responses in wheat-growing seasons. Additionally, such studies need to include potential variations in soil carbon(C) structure and microbial community composition. In this study, a long-term rice-wheat rotation P-input reduction experiment was conducted to observe the variations in soil P pools and C composition in the 7th wheat season and to investigate the responses of soil enzyme activity and microbial communities. Four P fertilization treatments were included in the experiment, i.e., P application for rice season only(PR), for wheat season only(PW), and for both rice and wheat seasons(PR+W) and no P application in either season(Pzero). Compared with PR+W treatment, Pzero treatment significantly decreased(P < 0.05) labile and stable P pools. Different P fertilization regimes altered soil microbial community composition and enzyme activity, whereas C composition did not vary. However, PW treatment resulted in relatively more O-alkyl-C than PR treatment and the highest number of microorganisms. Besides, the higher ratios of fungi/bacteria and Gram-positive bactetia/Gram-negative bactetia were related to labile C pools, particularly O-alkyl-C, as opposed to recalcitrant C. Our results clarified the status of soil P pools, C chemistry, and the response of microorganisms under dry-farming conditions in the P input-reduced rice-wheat rotation system. 相似文献
9.
Paolo NANNIPIERI Judith ASCHER-JENULL Maria Teresa CECCHERINI Giacomo PIETRAMELLARA Giancarlo RENELLA Michael SCHLOTER 《土壤圈》2020,30(1):5-17
Since the advent of sequencing technologies,the determination of microbial diversity to predict microbial functions,which are the major determinants of soil functions,has become a major topic of interest,as evidenced by the 900 publications dealing with soil metagenome published up to 2017.However,the detection of a gene in soil does not mean that the relative function is expressed,and the presence of a particular taxon does not mean that the relative functions determined in pure culture also occur in the studied soil.Another critical step is to link microbial community composition or function to the product analyzed to determine flux rates.Indeed,flux rates might not only be highly dynamic,but several metabolites can depend on different reactions,which makes the link to one process of interest difficult or even impossible.This review also discusses biases caused by sampling,storage of samples,DNA extraction and purification,sequencing(amplicon-vs.metagenome sequencing),and bioinformatic data analysis.Insights and the limits of predicting microbial interactions by network inference methods are critically discussed,and finally,future directions for a better understanding of soil functions by using measurements of microbial diversity are presented. 相似文献
10.
Xinhong GAN Ying TENG Jian XU Ning ZHANG Wenjie REN Ling ZHAO Peter CHRISTIE Yongming LUO 《土壤圈》2022,(2)
Clay minerals play an important role in biogeochemical cycling.Here,kaolinite and montmorillonite,the two most abundant and widespread clay minerals with typical layered structures,were selected to investigate and compare their effects on the biodegradation of benzo[a]pyrene(BaP)by Paracoccus aminovorans HPD-2 and to investigate the underlying interface mechanisms.Overall,the BaP degradation efficiency was significantly higher 7 d after montmorillonite addition,reaching 68.9%(P<0.05),when compared with that of the control without addition of clay minerals(CK,61.4%);however,the addition of kaolinite significantly reduced the BaP degradation efficiency to 45.8%.This suggests that kaolinite inhibits BaP degradation by inhibiting the growth of strain HPD-2,or its strong hydrophobicity and readily agglomerates in the degradation system,resulting in a decrease in the bio-accessibility of BaP to strain HPD-2.Montmorillonite may buffer some unfavorable factors,and cells may be fixed on the surface of montmorillonite colloidal particles across energy barriers.Furthermore,the adsorption of BaP on montmorillonite may be weakened after swelling,reducing the effect on the bio-accessibility of BaP,thus promoting the biodegradation of BaP by strain HPD-2.The experimental results indicate that differential bacterial growth,BaP bio-accessibility,interface interaction,and the buffering effect may explain the differential effects of the different minerals on polycyclic aromatic hydrocarbon biodegradation.These observations improve our understanding of the mechanisms by which clay minerals,organic pollutants,and degrading bacteria interact during the biodegradation process and provide a theoretical basis for increasing the biodegradation of soil pollutants by native microorganisms under field conditions. 相似文献
11.
Suyundukov Ya. T. Suyundukova M. B. Bezuglova O. S. Khabirov I. K. Khasanova R. F. Semenova I. N. Rafikova Yu. S. Ilbulova G. R. 《Eurasian Soil Science》2022,55(1):27-35
Eurasian Soil Science - The results of the study of the properties of urban soils of the city of Sibay located in the mining region of the Republic of Bashkortostan are presented. A specific... 相似文献
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物联网是一个集信息通信、数据交换、传感器技术与软件工程于一体的综合性产业,探讨和分析了物联网的结构体系与发展中遇到的安全问题。 相似文献
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荔枝种子从果实中剥离出来后, 即使在室内条件下, 也极易失水干缩, 潮湿环境中又易发霉而腐烂。扫描电镜观察表明: 种皮上布满纹孔, 水分散失面积很大; 种脐部为疏松的海绵组织, 且营养丰富。据此, 生产上应对种子彻底清洗, 并保存于适当湿度的环境中, 以提高其发芽率。 相似文献
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三门峡水库库岸坍塌成因分析与防治措施研究 总被引：10，自引：0，他引：10
三门峡水库自1960年9月蓄水运行以来,库岸坍塌现象频繁发生,平均每年塌岸0.5～0.7亿m3.指出了造成库岸坍塌的原因主要是地质环境的影响以及水力条件的变化;不同的地形、地貌、地质结构和岩性特征,表现了不同的塌岸强度,其中黄土塬区为极强塌岸段,黄河Ⅱ级阶地为强烈塌岸段,黄河Ⅰ级阶地为中等强烈塌岸段;分析了引起库岸坍塌的主要水力条件有大气降水、地表水和地下水,并且不同水力条件及其变化特征,对库岸坍塌影响的方式和程度也不同;最后给出了防治库岸坍塌应采用标本兼治的原则,治标是指对塌岸进行必要的加固、支挡、衬砌等;治本就是根据引起塌岸的原因以及不同地质环境条件下的塌岸特征和水力条件,因地制宜,因害设防,从根本上进行综合治理. 相似文献
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Kholodov V. A. Farkhodov Y. R. Yaroslavtseva N. V. Ziganshina A. R. Maksimovich S. V. 《Eurasian Soil Science》2022,55(7):998-1004
Eurasian Soil Science - Layers were step-by-step removed from macroaggregates (2–1 mm in diameter) of Protocalcic Chernozems via successive abrasion in a revolving rotator during 5, 10, 15,... 相似文献
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氟对小鼠生精细胞凋亡的影响及锌的保护作用 总被引：1，自引：0，他引：1
为观察氟对成年雄性小鼠生精细胞凋亡的影响及锌的保护作用,通过腹腔注射氟化钠建立氟中毒动物模型及锌保护实验。采用石蜡切片、苏木精-伊红染色(HE染色)、末端原位标记(TUNEL)及琼脂糖凝胶电泳的方法检测小鼠生精细胞的凋亡情况。结果显示:(1)氟感染组无论是低剂量组(NaF10 mg/kg)或是高剂量组(NaF 20 mg/kg)生精细胞都发生了明显的凋亡。生精细胞凋亡主要发生在精母细胞和精原细胞,凋亡指数与对照组差异极显著(P<0.05)。(2)无论是高剂量锌(ZnSO430 mg/kg)和低剂量锌(ZnSO415 mg/kg)都可以使凋亡指数明显降低,高剂量锌组的凋亡指数与对照组差异不显著(P>0.05)。 相似文献
20.
淤地坝坝体体积的计算 总被引：3，自引：1，他引：3
对于已确定的淤地坝坝址,坝体的纵断面（即沟道横断面）是一定的。根据实测的沟造横断面,以沟底最低点为坐标原点,沟道一侧的岸壁曲线可用幂函数形式表示之。利用这种幂函数关系,对于坝坡均一的坝体．在设定坝顶宽、坝高和上下游边坡之后,作者推导出沟道一侧坝体体积的计算公式;沟道两侧的坝体体积即为坝体总体积。对于非均一坝坡、设有马道的坝和坝体加高的体积,可将坝体横断面分割为由几个均一坝坡组成的坝体断面,分别计算其体积。这种计算方法的精度,取决于坝址横断面岸壁曲线回归方程与实际岸壁的符合程度。 相似文献