Gênese, química e mineralogia de solos derivados de sedimentos pliopleistocênicos e de rochas vulcânicas básicas em Roraima, Norte Amazônico

Benedetti, Udine Garcia; Júnior, José Frutuoso do Vale; Schaefer, Carlos Ernesto Gonçalves Reynaud; Melo, Valdinar Ferreira; Uchôa, Sandra Cátia Pereira

doi:10.1590/s0100-06832011000200002

Cited by 47 publications

(53 citation statements)

References 9 publications

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“…Analysis revealed the dominance of kaolinite, as well as small quantities of gibsite, illite, and quartz ( Figure 3). This result corroborates studies that evidence kaolinite as the main mineral of the clay fraction of Amazonian soils (Corrêa et al, 2008;Benedetti et al, 2011).…”

Section: Resultssupporting

confidence: 92%

“…The presence of this feature in deeper layers of the soil can be explained by the fluctuation of the water table and the influence of the rainfall period throughout the profile (Figure 2). High soil moisture contents in the soil profile for long periods of the year favor redox processes, which contribute to the solubilization and precipitation of Fe, as was evidenced by the redoximorphic features in the form of mottles, plinthite, and petroplinthite observed in the soils studied (Benedetti et al, 2011;Campos et al, 2012;Garcia et al, 2013;Santos et al, 2013b).…”

Section: Resultsmentioning

confidence: 82%

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Characterization and Classification of Soils under Forest and Pasture in an Agroextractivist Project in Eastern Amazonia

Zenero

Silva

Castilho

et al. 2016

Rev. Bras. Ciênc. Solo

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Knowledge of soils in the Amazon rainforest is becoming increasingly essential due to dynamics adopted by farmers that substitute forest for pastures, together with growing pressure from diverse segments of society towards adoption of sustainable production systems. The objective of this study was to characterize the soils along two toposequences, one under forest (F) and the other under pasture (P), and to verify how the change in land use influences soil attributes, evaluating their inclusion in the Brazilian Soil Classification System (SiBCS). The soils were sampled in pits located at the summit, backslope and footslope positions for morphological, chemical, physical, and clay mineralogy analysis. The results show that the soils are chemically poor and predominately kaolinitic. Sandy and loamy sand soils are in the surface horizons, with an increase in clay content with depth. The highest values of bulk density and lowest values of macroporosity were observed in the Bt horizons due to the change from a granular structure in the surface to an angular and subangular blocky structure in these horizons. The morphological properties observed in the field are strongly influenced by the annual soil water dynamics, the parent material, and the landscape, representing diagnostic characteristics that influenced classification of the soils, such as aquic with episaturation (epirredóxico), saprolitic, and gravelly. These diagnostic characteristics in the Argissolo Amarelo (Hapludults) are important morphological properties that have not been highlighted by the current edition of the SiBCS.

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Section: Resultssupporting

confidence: 92%

Section: Resultsmentioning

confidence: 82%

Characterization and Classification of Soils under Forest and Pasture in an Agroextractivist Project in Eastern Amazonia

Zenero

Silva

Castilho

et al. 2016

Rev. Bras. Ciênc. Solo

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“…Constatou-se com as análises física e química do solo que todas as áreas estudadas apresentavam solo arenoso e baixo teor de matéria orgânica e de potássio (Tabela 1), que são características naturais dos solos dos cerrados de Roraima (Benedetti et al 2011). Entretanto, em decorrência da correção e adubação durante o preparo do solo, as áreas cultivadas apresentaram teores mais elevados de Ca, Mg e P, comparativamente com a área de referência, não havendo diferenças expressivas entre elas (Tabela 1).…”

Section: Resultsunclassified

Dinâmica de rizóbios em solo do cerrado de Roraima durante o período de estiagem

et al. 2013

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A fixação biológica de nitrogênio que ocorre em leguminosas é realizada por um grupo de bactérias conhecidas como rizóbios. A sobrevivência destas bactérias no solo é influenciada por diversos fatores como a temperatura, umidade e fertilidade do solo. O objetivo deste trabalho foi avaliar a dinâmica da população de rizóbios em solo após o cultivo de soja, durante o período de estiagem no cerrado de Roraima. Foram amostradas três áreas: i) cerrado nativo como referência; ii) área cultivada uma vez com soja inoculada com rizóbio; iii) e área cultivada duas vezes com soja inoculada com rizóbio em anos consecutivos. O solo foi coletado na profundidade de 0-10 cm em cinco períodos a partir do inicio da estiagem no mês de setembro de 2006 coincidindo com a época de colheita da soja e prolongando-se até março de 2007 (0, 45, 90, 135 e 180 dias). A população de rizóbios no solo foi avaliada pela técnica do número mais provável (NMP) utilizando plantas de soja e de feijão-caupi como espécies isca. Foi observado que na área nativa praticamente não existiam bactérias nodulantes de soja, mas havia uma população capaz de nodular o feijão-caupi de até algumas centenas de rizóbios por gramas de solo. O cultivo da soja utilizando sementes inoculadas elevou a população de rizóbios no solo que foi constatada por ambas às espécies de plantas isca. Nas áreas cultivadas, constatou-se uma intensa redução da população de rizóbios no solo, em especial logo após a colheita da soja, continuando o decréscimo até o último período de avaliação. Conclui-se que o cultivo da soja inoculada com rizóbio eleva a densidade de rizóbios em solo do cerrado, mas durante a estiagem ocorre uma drástica redução dessa população, que pode chegar a mais de 99% considerando o início e final do período. PALAVRAS-CHAVE: Glycine max; Vigna unguiculata; nodulação; número mais provável. Dynamic of rhizobia in the soil during the dry season in cerrado of Roraima ABSTRACTThe biological nitrogen fixation in legumes is performed by a group of bacteria known as rhizobia. The survival of these bacteria in soils is affected by several factors, such as temperature, drought and soil fertility. This study was performed to evaluate the dynamics of rhizobia in the soil after soybean cultivation and during a dry season in the cerrado of Roraima. Three areas were sampled: i) native cerrado as reference; ii) an area previously cultivated with soybean for one season; and iii) another one cultivated for two seasons also with soybean. The soil was sampled at a depth of 0-10 cm in five times (0, 45, 90, 135 and 180 days) during the dry season (September 2006 to March 2007. The rhizobial density in the soil was evaluated by the most probable number method with infection of soybean and cowpea plants. It was observed very low number of soybean nodulating bacteria in the reference area, but a high density, of up to several hundred rhizobia capable to nodulate cowpea was measured in this same area. Cropping of soybean with inoculated seeds increased rhizobial density evaluated by both...

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“…), paricarana (Bowdichia virgilioides Kunth) e sucuba (Himatanthus articulathus (Vahl) Wood). Nas formações pioneiras ocorre o domínio de Buriti (Mauritia flexuosa L.) (BENEDETTI et al, 2011).…”

Section: Methodsunclassified

“…Em geral, esse solos são caracterizados como cauliníticos, com baixa saturação por bases, fortemente ácidos, com pH em água variando de 4,6 a 5,3 a moderadamente ácidos e bem drenados (BENEDETTI et al, 2011).…”

Section: Methodsunclassified

Composição da assembleia de formigas em área de savana no norte da Amazônia

Júnior

Lima

Cidade³

et al. 2017

AGRO@MBIENTE ON-LINE

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Resumo: Os formicídeos constituem um dos grupos mais importante de insetos sociais do solo, apontados como potenciais indicadores biológicos da degradação ambiental e fornecedores de informações importantes em planos de manejo e conservação de uma dada região. Assim, objetivou-se com este trabalho inventariar a composição da assembleia de formigas e estabelecer as espécies predominantes, utilizando dois diferentes métodos de coleta (pitfall e isca de sardinha), em ecossistema de savana amazônica. Abstract:The formicidae comprise one of the most important groups of social soil insects, identified as potential biological indicators of environmental degradation, and which provide important information in the management and conservation plans for any given region. The aim of this work therefore, was to inventory the composition of ant assembly and establish the predominant species, using two different collection methods (pitfall trap and sardine bait), in a savannah ecosystem of the Amazon. The ants were collected at six different times from December 2010 to January 2011. There were 12 plots, each 250 m in length, in which there were 10 sampling points spaced 25 m apart. At each point, two collection methods were used: pitfall trap and sardine bait, giving 120 subsamples per method. After collection, the samples were taken to the Aquatic Invertebrate Laboratory of the Centre for Biodiversity (CBIO/UFRR) for sorting, and the specimens placed into bottles containing 70% alcohol for later taxonomic classification. Identification of the formicidae as to species and morphospecies was carried out at the National Research Institute of the Amazon (INPA). All materials were deposited in the invertebrate collection of INPA. It was found that the genera with greater occurrence were Camponotus, Crematogaster and Dorymyrmex, while those with the greatest species richness were Pheidole, Solenopsis and Camponotus. The species Crematogaster abstinens and Camponotus novogranadensis were predominant in the area of savannah under study. This is the first record of Kalathomyrmex emeryi in the State of Roraima. The collections made with pitfall traps were more efficient for evaluating ant richness.

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Gênese, química e mineralogia de solos derivados de sedimentos pliopleistocênicos e de rochas vulcânicas básicas em Roraima, Norte Amazônico

Cited by 47 publications

References 9 publications

Characterization and Classification of Soils under Forest and Pasture in an Agroextractivist Project in Eastern Amazonia

Characterization and Classification of Soils under Forest and Pasture in an Agroextractivist Project in Eastern Amazonia

Dinâmica de rizóbios em solo do cerrado de Roraima durante o período de estiagem

Composição da assembleia de formigas em área de savana no norte da Amazônia

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