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Biomassa microbiana do solo sob sistema de plantio direto na região de Campos Gerais, Tibagi, PR. ; Soil microbial biomassa under no-tillage in the region of campos gerais, Tibagi, PR.

Venzke Filho, Solismar de Paiva
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 04/12/2003 Português
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A demanda por informações relativas à ciclagem de nutrientes no solo sob sistema plantio direto (SPD) motivou o estudo das variações da biomassa microbiana do solo (BMS) em áreas com diferentes texturas submetidas há longo tempo a esse tipo de manejo. Na região de Campos Gerais, Tibagi (PR) é adotada a seqüência de culturas soja e milho no verão, seguidos de trigo e aveia preta no inverno há mais de 20 anos. O objetivo foi monitorar as variações do C e N-microbianos durante um ciclo de rotação em quatro áreas, sendo três com histórico de 12 anos sob SPD, com textura muito argilosa (PD12-TmuA), argilosa (PD12-TA), e média argilosa (PD12-TmeA), e uma com histórico de 22 anos sob SPD com textura argilosa (PD22-TA). No período de 18 meses foram realizadas nove amostragens de solo em quatro camadas (0-2,5; 2,5-5; 5-10; 10-20 cm). Foram avaliadas também alguns parâmetros das raízes do milho e da soja no PD22-TA visando determinar a influência de culturas distintas (plantas C4 e C3) sobre a concentração de BM no perfil do solo. A diferença de dez anos no tempo de adoção do SPD determinou aumento do C-microbiano no PD22-TA sobre o PD12-TA nas camadas mais profundas do solo. O PD22-TA também apresentou em média 30...

Padrões de diversidade microbiana em sedimentos marinhos profundos influenciados por uma exsudação de asfalto.; Microbial diversity patterns in deep-sea sediments influencied by asphalt seep.

Queiroz, Luciano Lopes
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 26/05/2015 Português
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Sedimentos de mar profundo são ambientes estáveis e homogêneos, apesar disso, eles apresentam uma grande variedade de habitats disponíveis, possibilitando uma alta diversidade microbiana. A distribuição espacial dos micro-organismos é influenciada por fatores locais e regionais. Os fatores locais são associados à estrutura do ambiente e os fatores regionais, a limitação na dispersão dos micro-organismos que compõem as comunidades e eventos históricos que eventualmente podem modificar o ambiente. Eventos como a liberação de hidrocarbonetos das camadas mais profundas do sedimento para superfície podem alterar os padrões de distribuição espacial das comunidades microbianas, devido o aumento na disponibilidade de carbono e consequentemente selecionando as espécies capazes de degradá-los. Esses eventos são denominados de exsudações de asfalto e foram encontradas na região de estudo. Considerando a falta de conhecimento e a importância dos micro-organismos em sedimentos de mar profundo do oceano Atlântico Sul, o objetivo desse estudo foi compreender os padrões de diversidade microbiana nessas regiões e também investigar como o óleo proveniente da exsudação de asfalto influência as comunidades de micro-organismos no seu entorno. Esse estudo foi realizado na região do Platô de São Paulo que foi dividido em duas regiões...

Carga microbiana de trocartes reprocessaveis apos laparoscopias ginecologicas; Microbial load of reusables trocars after gynecology laparoscopy

Vanessa Aparecida Vilas-Boas
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 29/07/2009 Português
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A transmissão de infecções hospitalares está relacionada à sobrevivência de microrganismos nas superfícies ambientais e no instrumental cirúrgico. Nos últimos anos, o Brasil tem se deparado com um cenário disperso em relação à validação do processo de limpeza e esterilização de instrumentos cirúrgicos utilizados em acessos minimamente invasivos, principalmente os procedimentos realizados por vídeo. Para implantação de medidas eficazes no reprocessamento é necessário saber como está o material em termos de contaminação e verificar se a carga microbiana trazida por esse instrumental é superior ao desafio microbiano imposto pelos indicadores biológicos. Deste modo, espera-se que a análise quanti-qualitativa dos microrganismos presentes em instrumentos cirúrgicos laparoscópicos após o uso clínico possa nortear a tomada de decisão pelos profissionais de saúde a contribuir para a melhoria do processo de trabalho visando à segurança do paciente. Objetivo: Identificar a carga microbiana presente nos trocartes reprocessáveis de 5 mm e 10 mm, usados para realização de laparoscopias ginecológicas. Material e Método: Tratase de um estudo exploratório descritivo. Um total de 57 trocartes de 5 mm e 10 mm de diâmetro foi recolhido na sala de operação...

Hydrogen producing microbial communities of the biocathode in a microbial electrolysis cell

Croese, E.; Pereira, M. A.; Euverink, G.; Stams, A. J. M.; Geelhoed, J.
Fonte: International Society for Microbial Ecology Publicador: International Society for Microbial Ecology
Tipo: Conferência ou Objeto de Conferência
Publicado em 22/08/2010 Português
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In the search for alternatives for fossil fuels and the reuse of the energy from waste streams, the microbial electrolysis cell is a promising technique. The microbial electrolysis cell is a two electrode system in which at the anode organic substances, including waste water, are used by microorganisms that release the terminal electrons to the electrode. These electrons are subsequently used at the cathode resulting in the production of a current. By addition of a small voltage, hydrogen gas can be produced by combining electrons and protons at the cathode. To catalyse the hydrogen evolution reaction at the cathode, expensive catalysts such as platinum are required. Recently, the use of biocathodes has shown great potential as an alternative for platinum. The microbial community responsible for the hydrogen evolution in such systems is, however, not well understood. In this study we focused on the characterization of the microbial communities of the microbial electrolysis cell biocathode using molecular techniques. The results show that the microbial community consists of 44% Proteobacteria, 27% Firmicutes, 18% Bacteriodetes and 12% related to other phyla. Within the major phylogenetic groups we found several clusters of uncultured species belonging to novel taxonomic groups at genus level. These novel taxonomic groups developed under environmentally unusual conditions and might have properties that have not been described before. Therefore it is of great interest to study those novel groups further. Within the Proteobacteria a major cluster belonged to the Deltaproteobacteria and based on the known characteristics of the closest related cultured species...

Soil microbial biomass under mulch types in an integrated apple orchard from Southern Brazil

Almeida,Denice de Oliveira; Klauberg Filho,Osmar; Almeida,Henrique Cesar; Gebler,Luciano; Felipe,Aline Franciane
Fonte: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz" Publicador: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz"
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2011 Português
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The use of mulching is an alternative to control weeds but there are few studies on its effect on soil quality. In this sense, this study aimed to evaluate the effect of types of mulching on the attributes of microbial carbon, nitrogen and phosphorus in a Typic Hapludox with production of integrated apples in southern Brazil. The experiment was conducted in randomized blocks in the Vacaria, state of Rio Grande do Sul, southern Brazil. The soil mulch types studied were: pine needle, sawdust, black plastic and a control. The soil samples were collected in February (summer) and August (winter) of 2006, and the attributes related to total organic and microbial carbon, nitrogen and phosphorus were determined. Organic mulchings (pine needle and sawdust) promoted lower soil temperature, and greater moisture, microbial carbon (Cmic), microbial nitrogen (Nmic), and the ratios Cmic:Corg, Nmic:Norg and microbial C:N than black plastic. Microbial phosphorus was greater in winter. Sawdust mulching promoted the best conditions to microbial biomass in winter. The mulch types increased the microbial compartment in winter as compared to the nonweeded control .

Association of Microbial Community Composition and Activity with Lead, Chromium, and Hydrocarbon Contamination

Shi, W.; Becker, J.; Bischoff, M.; Turco, R. F.; Konopka, A. E.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /08/2002 Português
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Microbial community composition and activity were characterized in soil contaminated with lead (Pb), chromium (Cr), and hydrocarbons. Contaminant levels were very heterogeneous and ranged from 50 to 16,700 mg of total petroleum hydrocarbons (TPH) kg of soil−1, 3 to 3,300 mg of total Cr kg of soil−1, and 1 to 17,100 mg of Pb kg of soil−1. Microbial community compositions were estimated from the patterns of phospholipid fatty acids (PLFA); these were considerably different among the 14 soil samples. Statistical analyses suggested that the variation in PLFA was more correlated with soil hydrocarbons than with the levels of Cr and Pb. The metal sensitivity of the microbial community was determined by extracting bacteria from soil and measuring [3H]leucine incorporation as a function of metal concentration. Six soil samples collected in the spring of 1999 had IC50 values (the heavy metal concentrations giving 50% reduction of microbial activity) of approximately 2.5 mM for CrO42− and 0.01 mM for Pb2+. Much higher levels of Pb were required to inhibit [14C]glucose mineralization directly in soils. In microcosm experiments with these samples, microbial biomass and the ratio of microbial biomass to soil organic C were not correlated with the concentrations of hydrocarbons and heavy metals. However...

Seasonal and Spatial Distribution of Extracellular Enzymatic Activities and Microbial Incorporation of Dissolved Organic Substrates in Marine Sediments

Meyer-Reil, Lutz-Arend
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /08/1987 Português
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Seasonal and spatial distributions of extracellular enzymatic activities and microbial incorporations of dissolved organic substrates were followed in sediments of the brackish water Kiel Bight (Baltic Sea, Federal Republic of Germany). Enzymatic hydrolysis of polymeric organic compounds was determined by means of fluorogenic substrates (4-methylumbelliferyl-β-d-glucoside, l-leucine-4-methylcoumarinyl-7-amide hydrochloride); incorporation of dissolved organic substrates into microbial biomass was measured by using tritiated substances (acetate, leucine, and thymidine). Based on a recently developed core injection technique, substrates were injected in microliter portions into undisturbed sediment cores. Enzymatic and incorporation activities underwent strong seasonal variations related to the enrichment of organic material in the sediment surface following sedimentation events. The input of the phytoplankton bloom during autumn caused stimulation of both enzymatic hydrolysis of polymeric organic compounds and microbial incorporation of dissolved organic substrates. Following input by spring phytoplankton bloom, mainly incorporation activities were stimulated. In late spring the development of the benthic fauna obviously greatly influenced microbial activities. During summer individual periods of high microbial activities were observed which might be traced back to short-term sedimentation events. The high microbial incorporation of leucine and thymidine during winter demonstrated that the nutrient supply rather than temperature is the dominating factor determining microbial production. Stimulation of microbial activities arose from the sediment surface and spread out relatively quickly into deeper horizons. Generally...

Seasonal Changes in the Rhizosphere Microbial Communities Associated with Field-Grown Genetically Modified Canola (Brassica napus)

Dunfield, Kari E.; Germida, James J.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /12/2003 Português
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The introduction of transgenic plants into agricultural ecosystems has raised the question of the ecological impact of these plants on nontarget organisms, such as soil bacteria. Although differences in both the genetic structure and the metabolic function of the microbial communities associated with some transgenic plant lines have been established, it remains to be seen whether these differences have an ecological impact on the soil microbial communities. We conducted a 2-year, multiple-site field study in which rhizosphere samples associated with a transgenic canola variety and a conventional canola variety were sampled at six times throughout the growing season. The objectives of this study were to identify differences between the rhizosphere microbial community associated with the transgenic plants and the rhizosphere microbial community associated with the conventional canola plants and to determine whether the differences were permanent or depended on the presence of the plant. Community-level physiological profiles, fatty acid methyl ester profiles, and terminal amplified ribosomal DNA restriction analysis profiles of rhizosphere microbial communities were compared to the profiles of the microbial community associated with an unplanted...

Spatial Distribution of Viruses Associated with Planktonic and Attached Microbial Communities in Hydrothermal Environments

Yoshida-Takashima, Yukari; Nunoura, Takuro; Kazama, Hiromi; Noguchi, Takuroh; Inoue, Kazuhiro; Akashi, Hironori; Yamanaka, Toshiro; Toki, Tomohiro; Yamamoto, Masahiro; Furushima, Yasuo; Ueno, Yuichiro; Yamamoto, Hiroyuki; Takai, Ken
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /03/2012 Português
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Viruses play important roles in marine surface ecosystems, but little is known about viral ecology and virus-mediated processes in deep-sea hydrothermal microbial communities. In this study, we examined virus-like particle (VLP) abundances in planktonic and attached microbial communities, which occur in physical and chemical gradients in both deep and shallow submarine hydrothermal environments (mixing waters between hydrothermal fluids and ambient seawater and dense microbial communities attached to chimney surface areas or macrofaunal bodies and colonies). We found that viruses were widely distributed in a variety of hydrothermal microbial habitats, with the exception of the interior parts of hydrothermal chimney structures. The VLP abundance and VLP-to-prokaryote ratio (VPR) in the planktonic habitats increased as the ratio of hydrothermal fluid to mixing water increased. On the other hand, the VLP abundance in attached microbial communities was significantly and positively correlated with the whole prokaryotic abundance; however, the VPRs were always much lower than those for the surrounding hydrothermal waters. This is the first report to show VLP abundance in the attached microbial communities of submarine hydrothermal environments...

Microbial Community Dynamics of an Urban Drinking Water Distribution System Subjected to Phases of Chloramination and Chlorination Treatments

Hwang, Chiachi; Ling, Fangqiong; Andersen, Gary L.; LeChevallier, Mark W.; Liu, Wen-Tso
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /11/2012 Português
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Water utilities in parts of the U.S. control microbial regrowth in drinking water distribution systems (DWDS) by alternating postdisinfection methods between chlorination and chloramination. To examine how this strategy influences drinking water microbial communities, an urban DWDS (population ≅ 40,000) with groundwater as the source water was studied for approximately 2 years. Water samples were collected at five locations in the network at different seasons and analyzed for their chemical and physical characteristics and for their microbial community composition and structure by examining the 16S rRNA gene via terminal restriction fragment length polymorphism and DNA pyrosequencing technology. Nonmetric multidimension scaling and canonical correspondence analysis of microbial community profiles could explain >57% of the variation. Clustering of samples based on disinfection types (free chlorine versus combined chlorine) and sampling time was observed to correlate to the shifts in microbial communities. Sampling location and water age (<21.2 h) had no apparent effects on the microbial compositions of samples from most time points. Microbial community analysis revealed that among major core populations, Cyanobacteria, Methylobacteriaceae...

Cross-Site Soil Microbial Communities under Tillage Regimes: Fungistasis and Microbial Biomarkers

Sipilä, Timo P.; Yrjälä, Kim; Alakukku, Laura; Palojärvi, Ansa
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /12/2012 Português
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The exploitation of soil ecosystem services by agricultural management strategies requires knowledge of microbial communities in different management regimes. Crop cover by no-till management protects the soil surface, reducing the risk of erosion and nutrient leaching, but might increase straw residue-borne and soilborne plant-pathogenic fungi. A cross-site study of soil microbial communities and Fusarium fungistasis was conducted on six long-term agricultural fields with no-till and moldboard-plowed treatments. Microbial communities were studied at the topsoil surface (0 to 5 cm) and bottom (10 to 20 cm) by general bacterial and actinobacterial terminal restriction fragment length polymorphism (T-RFLP) and phospholipid fatty acid (PLFA) analyses. Fusarium culmorum soil fungistasis describing soil receptivity to plant-pathogenic fungi was explored by using the surface layer method. Soil depth had a significant impact on general bacterial as well as actinobacterial communities and PLFA profiles in no-till treatment, with a clear spatial distinction of communities (P < 0.05), whereas the depth-related separation of microbial communities was not observed in plowed fields. The fungal biomass was higher in no-till surface soil than in plowed soil (P < 0.07). Soil total microbial biomass and fungal biomass correlated with fungistasis (P < 0.02 for the sum of PLFAs; P < 0.001 for PLFA 18:2ω6). Our cross-site study demonstrated that agricultural management strategies can have a major impact on soil microbial community structures...

Bioensaios com fósforo e indicadores químicos, microbianos e bioquímicos do solo, em áreas sob cerrado, pinus e plantio direto; Phosphorus bioassays and chemical, microbial and biochemical indicators of soil in areas under savannah, pinus forest and no-tillage

Vinhal-Freitas, Isabel Cristina
Fonte: Universidade Federal de Uberlândia Publicador: Universidade Federal de Uberlândia
Tipo: Dissertação
Português
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A atividade microbiana no solo exerce grande importância na regulação dos processos de transformação de carbono e nutrientes, a exemplo do fósforo. No entanto, a atividade da microbiota é fortemente ligada a práticas agrícolas de uso do solo. No capítulo I, o trabalho teve como objetivo comparar três sistemas de uso do solo, em relação à resposta da atividade microbiana e metabólica, quando da adição de fósforo e glicose em Latossolo fase cerrado. Os sistemas de uso do solo foram: área de cerrado (CE), floresta de pinus com árvores de 32 anos (FP) e plantio direto (PD) com 11 anos. As amostras de solos foram coletadas na profundidade de 0-10 cm, nos meses de janeiro, junho e dezembro de 2008, e foram avaliadas quanto ao carbono liberado (C-CO2) pela atividade microbiana; carbono orgânico total (COT); carbono da biomassa microbiana (CBM); glicose total (GT) e rendimento metabólico. A adição de doses crescentes de P aumentou a atividade respiratória dos solos dos três sistemas de uso. A adição de P aumentou a atividade microbiana (atividade respiratória, com incremento em biomassa microbiana) e rendimento metabólico (eficiência de utilização da glicose), principalmente se adicionado junto com uma fonte de carbono (glicose). O uso de testes de incubação do solo com adição de nutrientes pode ser usado para caracterizar o potencial de resposta metabólica de solos com características de uso diferentes...

Soil microbial activity and community structure as affected by osmotic and matric potential.

Chowdhury, Nasrin
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2011 Português
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36.57%
Salinization of soils is a serious land degradation problem, causing poor plant growth and low microbial activity due to osmotic stress, ion toxicity and imbalanced element uptake. In arid, semi arid or seasonally arid (Mediterranean) regions, low or fluctuating matric potential causes further stress to soil microorganisms in saline soil by decreasing the osmotic potential as salts in the soil solution become more concentrated, as well as by reducing diffusion and thus substrate availability. Soil properties such as soil texture, water retention characteristics and organic matter content also influence soil microbial activity and community structure and the effect of salinity and matric potential on soil microorganisms. While the effects of low matric and low osmotic potential on soil microorganisms have been studied separately, little is known about their interaction. The objective of this thesis was to determine the interaction between soil matric and osmotic potential on soil microbial activity and community structure. Most experiments described in this thesis were carried out with two non-saline soils (sand and sandy loam) differing in nutrient status, microbial biomass and community composition. Osmotic stress was induced by application of different rates of NaCl. In all experiments...

Response of microbial activity and biomass to increasing salinity depends on the final salinity, not the original salinity

Yan, N.; Marschner, P.
Fonte: Pergamon-Elsevier Science Ltd Publicador: Pergamon-Elsevier Science Ltd
Tipo: Artigo de Revista Científica
Publicado em //2012 Português
Relevância na Pesquisa
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Salinization is a global land degradation issue which inhibits microbial activity and plant growth. The effect of salinity on microbial activity and biomass has been studied extensively, but little is known about the response of microbes from different soils to increasing salinity although soil salinity may fluctuate in the field, for example, depending on the quality of the irrigation water or seasonally. An incubation experiment with five soils (one non-saline, four saline with electrical conductivity (ECe) ranging from 1 to 50 dS m−1) was conducted in which the EC was increased to 37 ECe levels (from 3 to 119 dS m−1) by adding NaCl. After amendment with 2% (w/w) pea straw to provide a nutrient source, the soils were incubated at optimal water content for 15 days, microbial respiration was measured continuously and chloroform-labile C was determined every three days. Both cumulative respiration and microbial biomass (indicated by chloroform-labile C) were negatively correlated with EC. Irrespective of the original soil EC, cumulative respiration at a given adjusted EC was similar. Thus, microorganisms from previously saline soils were not more tolerant to a given adjusted EC than those in originally non-saline soil. Microbial biomass in all soils increased from day 0 to day 3...

Microbial biomass, nutrient availability and nutrient uptake by wheat in two soils with organic amendments

Malik, M.; Khan, K.; Marschner, P.; Ul-Hassan, F.
Fonte: Sociedad Chilena de la Ciencia del Suelo Publicador: Sociedad Chilena de la Ciencia del Suelo
Tipo: Artigo de Revista Científica
Publicado em //2013 Português
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A 72-day greenhouse pot experiment was conducted with a sandy loam or a silt loam soil to examine the effects of farmyard manure (FYM), poultry litter (PL) and biogenic waste compost (BWC) at 10 g dw kg-1 soil on microbial biomass and activity and growth and nutrient uptake by wheat. Soil samples were collected at days 0, 14, 28, 42, 56 and 72 after planting. Growth and nutrient uptake by wheat were determined on day 72. All three amendments increased microbial biomass C, N and P, dehydrogenase activity, plant growth and nutrient uptake with a greater effect by FYM and PL than by BWC. All amendments increased microbial biomass C, N and P and enzyme activity particularly on day 0. These microbial parameters decreased after day 0 indicating microbial biomass turnover. All amendments increased plant growth and nutrient uptake. It is concluded that organicamendments can stimulate microbial growth and nutrient uptake as well as plant growth and nutrient uptake. Microbes can increase plant nutrient availability by nutrient mobilisation but also because nutrients taken up by the microbial biomass initially could become available to plants when the microbial biomass turns over as the easily available C is depleted.; M.A. Malik, K.S. Khan, P. Marschner...

Microbial activity and biomass in saline soils as affected by carbon availability.

Elmajdoub, Bannur Mohamed Ahmed
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2014 Português
Relevância na Pesquisa
36.61%
Soil salinity is a serious land degradation problem which reduces plant growth and microbial activity due to (1) low osmotic potential which causes plant water stress, and (2) ion toxicity and ion imbalances (nutrient deficiencies) as result of high salt concentrations in the soil solution. Therefore, salinity affects organic matter turnover by influencing the amount of organic matter input in the soil and decomposition rate. Microbial activity and biomass in saline soils have been extensively studied, but a little is known about the effect of organic carbon (OC) addition on adaptation of soil microbes to salinity. The objective of this thesis was to determine the effect of OC availability on adaptation of soil microbial activity and biomass to salinity. In most experiments described in this thesis, one non-saline and four saline soils from the field with similar texture (sandy clay loam) and electrical conductivities in a 1:5 soil: water extract (EC₁﹕₅) of 0.1, 1.1, 3.1 and 5.2 dS m⁻¹ or electrical conductivity of the saturation extract (ECₑ) of 1, 11, 24 and 43 dS m⁻¹ were used. In other experiments a non-saline loamy sand was amended with NaCl to achieve a range of EC levels. The optimum water content for respiration was determined by incubating the soils amended with glucose at different water contents and measuring the respiration for 10 days at 25ºC. Glucose...

Response of microbial activity and biomass to changes in soil salinity and water content.

Yan, Nan
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2014 Português
Relevância na Pesquisa
36.58%
Salinization is a serious land degradation problem because osmotic stress and toxic ions cause poor plant growth and low soil microbial activity. The effect of salinity on soil microbes has been studied previously, but usually at constant salinity. However, in the field salinity may vary over time. Another factor influencing the effect of salinity on soil microbes is the soil water content. The osmotic potential, which is a measure of the salt concentration in the soil solution, increases as soils dry. The aim of the experiments described in this thesis was to assess how soil microbial activity and microbial biomass respond to changes in soil salinity and soil water content. One non-saline and four saline soils from Monarto, South Australia (35° 05´ S and 139° 06´ E) were used in the experiments. Soils were air-dried after collection. In some experiments, salinity was induced by adding certain amount of NaCl (dissolved in RO water), or decreased by leaching. Preliminary experiments were carried out to quantify the salts or water needed to reach the desired salinity. Pea (Pisum sativum L.) straw (C/N=26) was used as available substrate in most experiments except for experiments in Chapter four, where glucose was used. Soil CO₂ release (respiration as measure of microbial activity) was measured daily throughout each experimental period...

EFFECT OF WATER AVAILABILITY ON SOIL MICROBIAL BIOMASS IN SECONDARY FOREST IN EASTERN AMAZONIA

Rangel-Vasconcelos,Lívia Gabrig Turbay; Zarin,Daniel Jacob; Oliveira,Francisco de Assis; Vasconcelos,Steel Silva; Carvalho,Cláudio José Reis de; Santos,Maria Marly de Lourdes Silva
Fonte: Sociedade Brasileira de Ciência do Solo Publicador: Sociedade Brasileira de Ciência do Solo
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2015 Português
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Soil microbial biomass (SMB) plays an important role in nutrient cycling in agroecosystems, and is limited by several factors, such as soil water availability. This study assessed the effects of soil water availability on microbial biomass and its variation over time in the Latossolo Amarelo concrecionário of a secondary forest in eastern Amazonia. The fumigation-extraction method was used to estimate the soil microbial biomass carbon and nitrogen content (SMBC and SMBN). An adaptation of the fumigation-incubation method was used to determine basal respiration (CO2-SMB). The metabolic quotient (qCO2) and ratio of microbial carbon:organic carbon (CMIC:CORG) were calculated based on those results. Soil moisture was generally significantly lower during the dry season and in the control plots. Irrigation raised soil moisture to levels close to those observed during the rainy season, but had no significant effect on SMB. The variables did not vary on a seasonal basis, except for the microbial C/N ratio that suggested the occurrence of seasonal shifts in the structure of the microbial community.

Do plant clumps constitute microbial hotspots in semiarid Mediterranean patchy landscapes?

Goberna, M.; Pascual, Juan Antonio; García Izquierdo, Carlos; Sánchez Díaz, Juan
Fonte: Elsevier Publicador: Elsevier
Tipo: Artículo Formato: 259768 bytes; application/pdf
Português
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36.52%
8 pages, 4 figures, 2 tables.; Three semiarid Mediterranean patchy landscapes were investigated to test the existence of a microsite effect (i.e. plant canopy vs. inter-canopy) on soil microbial communities. Surface soil samples were independently taken from both microsites under naturally changing conditions of humidity and temperature through the year. In gypsiferous soils covered with a shrub steppe, improved physical and chemical soil properties were registered underneath the plant canopy, where the densest and most active microbial communities were also detected (e.g. microbial biomass C averaged 531 and 202 mg kg−1 in canopy and inter-canopy areas, respectively). In calcareous perennial tussock grasslands, either growing on soils over limestones or alluvial deposits, the microsite effect was not so marked. Soil humidity, temperature and total organic C were homogeneously distributed over the landscape conditioning their uniform microbial activity under field moisture conditions (ATP content averaged 853 and 885 nmol kg−1 in canopy and intercanopy areas, respectively). However, readily mineralizable C and microbial biomass C were preferentially accumulated in soils underneath the tussocks determining their larger potential microbial activity (e.g. C hydrolysis capacity under optimal conditions). In conclusion...

Biomassa microbiana do solo sob coberturas em pomar integrado de maçãs no Sul do Brasil; Soil microbial biomass under mulch types in an integrated apple orchard from Southern Brazil

Almeida, Denice de Oliveira; Klauberg Filho, Osmar; Almeida, Henrique Cesar; Gebler, Luciano; Felipe, Aline Franciane
Fonte: Universidade de São Paulo. Escola Superior de Agricultura Luiz de Queiroz Publicador: Universidade de São Paulo. Escola Superior de Agricultura Luiz de Queiroz
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; ; ; Formato: application/pdf
Publicado em 01/04/2011 Português
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The use of mulching is an alternative to control weeds but there are few studies on its effect on soil quality. In this sense, this study aimed to evaluate the effect of types of mulching on the attributes of microbial carbon, nitrogen and phosphorus in a Typic Hapludox with production of integrated apples in southern Brazil. The experiment was conducted in randomized blocks in the Vacaria, state of Rio Grande do Sul, southern Brazil. The soil mulch types studied were: pine needle, sawdust, black plastic and a control. The soil samples were collected in February (summer) and August (winter) of 2006, and the attributes related to total organic and microbial carbon, nitrogen and phosphorus were determined. Organic mulchings (pine needle and sawdust) promoted lower soil temperature, and greater moisture, microbial carbon (Cmic), microbial nitrogen (Nmic), and the ratios Cmic:Corg, Nmic:Norg and microbial C:N than black plastic. Microbial phosphorus was greater in winter. Sawdust mulching promoted the best conditions to microbial biomass in winter. The mulch types increased the microbial compartment in winter as compared to the nonweeded control .; O uso da cobertura do solo é alternativa para o controle de plantas daninhas. Entretanto há poucos estudos sobre seu efeito na qualidade do solo. Avaliou-se...