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The increasing concern regarding the preservation of soil quality suggests the adoption of quality reference values as a first step in environmental monitoring actions. In this context, the objective of this study was to establish soil quality reference values for Al, Zn, Mn, Cd, Fe, Pb, Ni, Cr, and Cu and to correlate several soil properties with the occurrence of these elements in the hillslope region of Rio de Janeiro State. Sixty-two samples were collected at depths of 0-20 and 20-40 cm and analyzed using the USEPA method 3051A. After clustering analysis, the samples were separated into three groups. Classification functions were obtained based on the variables pH - Mg - Fe - Mn, i.e., the variables that were best related to heavy metal content. We determined to establish the quality reference values for the 75th percentile of the three groups. The relief forms of the area, which facilitate the transport of soil fine-particle fractions and accumulation in lowlands, were revealed to be one of most important factors in understanding the distribution of soil heavy metals.

Located in the south-western part of Brazil, the state of Rio de Janeiro is geotectonically contained within a complex structural province that resulted in the amalgamation of the Western Gondwana Paleocontinent. To undertake an extensive radiological characterization of this complex geological province and investigate the influence of bedrock, soil type and soil chemical-physical characteristics on natural radionuclide levels in soils, 259 surface soil samples were collected that encompassed the main soil types and geological formations throughout the state. Gamma spectrometry analysis of the samples resulted in median values of 114 Bq.kg-1for 40K, 32 Bq.kg-1 for 226Ra and 74 Bq.kg-1 for 228Ra. The median value for 226Ra was similar to the world median value for soils, the 40K value was well below the worldwide value, and that for 228Ra exceeded the world median value. The intense weathering caused by the high rainfall rates and high temperatures may be responsible for the low levels of 40K in the soils, of which the strongly acidic and clayey soils are markedly K-depleted. A soil from a high-grade metamorphic rock (granulite) presented the lowest 226Ra (18 Bq.kg-1) content, whereas the highest levels for 226Ra (92 Bq.kg-1) and 228Ra (139 Bq.kg-1) were observed in a young soil enriched in primary minerals (Leptsol). A lowland soil (Gleysol) showed the highest median of 40K (301 Bq.kg-1). Strongly acidic soils tended to present high amounts of 226Ra, and sandy soils tended to contain low levels of 228Ra. The external radiation dose indicates that the state has a background radiation level within the natural range.

The distribution of fallout 137 Cs in soil samples of the Rio de Janeiro State was investigated. Two-hundred sixty-two samples of soil were analyzed for 137 Cs by gamma spectrometry. A reference data set was built containing thirty-six detected values (14%) and two hundred twenty-six (86%) multiple detection limits of non-detected observations. Distribution pattern of the radionuclide, as well their controlling factors were evaluated based on statistical methods for censored data set (with non-detected observations). The mean of concentration values of thirty-six detected observations was 1.25 Bq.kg -1 , while for the censored data sets the mean value was 0.51 Bq.kg -1 . The references values for the Rio de Janeiro State were estimated as 1.44 Bq.kg -1 (75 th ) and 1.78 Bq.kg - 1 (90 Th ) (considering the year of 2015). 137 Cs concentrations tend to be higher in soils with high levels of organic matter and clay and locations with high levels of these parameters would provide higher Cs fixation. No influence of the rainfall index and soil pH on the Cs content in soil was observed. The data and information gathered in this study provide valuable information for decision making purposes in case of soil contamination.

The diversity of methods for heavy metal extraction from soils complicates comparison of results used by environmental agencies to establish quality reference values. The aim of this study was to evaluate three soil digestion methods regarding the solubilizing capacity of Ba, Cr, Cu, Fe, Mn, Ni, Pb and Zn, and to propose a standard method to establish Quality Reference Values (QRVs) for Brazilian Histosols. Twenty soil samples were selected to evaluate the USEPA 3051, USEPA 3051A and Aqua Regia methods in a closed system. The methods tested were statistically similar regarding Cu, Fe and Mn extraction from soils. However, the methods can not be considered similar for Ba, Cr, Ni, Pb and Zn; Aqua Regia recorded the highest levels, except for Ba. The Aqua Regia method proved suitable for metal extraction from soils with organic characteristics and can be used to establish QRVs. Made available in DSpace on 2021-09-10T15:07:08Z (GMT). No. of bitstreams: 1 Comparing-methods-for-extracting-heavy-metals-from-Histosols-2016.pdf: 458412 bytes, checksum: 351e0ec0770742b76efdd86c5f12537b (MD5) Previous issue date: 2016

a b s t r a c t Sowing seeds with high concentrations of P or Mo can improve growth and nodulation of common bean (Phaseolus vulgaris) plants. However, the performance of the bean crop originating from seeds enriched with P and Mo has not yet been assessed under field conditions. This study aimed to evaluate the effect of sowing seeds enriched with P and Mo, harvested from plants that received foliar sprayings of P or Mo or both, on growth and yield of common bean crop. Seeds with contrasting concentrations of P and Mo were sown in three field experiments in Brazil (in 2006 and 2008 in Rio de Janeiro State, and in 2009 in Goias State) with different N sources (control without N, seed with rhizobia inoculation, rhizobia inoculation plus 40 kg N ha −1 side-dressed, mineral N with 60 kg N ha

Soil formation factors such as lateral and base water flows promote the Oxisol–Ultisol transformation on hillslopes in colluvium material with oxic properties. Chemical and electrochemical processes occur simultaneously with the morphological transformation of the soil structure from very fine granular to blocky soil. Statistical analysis techniques, such as principal component analysis (PCA) and hierarchical cluster analysis (HCA), were used to analyze the data collected from two sites in the state of Sao Paulo, Brazil, allowing a comprehensive description of the processes that entailed the transformation of an oxic horizon to a kandic horizon. The modeling power and the discriminating power from the soft independent modeling of class analogy (SIMCA) method were employed to find which attributes were essential to explain the transformation of an oxic into an argillic horizon. The following attributes were used to describe the processes in the toposequences studied: (a) index of silica reactivity (ISR); (b) index of silica saturation (ISS); (c) ratio of iron extracted with ammonium oxalate, DCB and H 2 SO 4 ; (d) ratio of aluminum extracted with ammonium oxalate, DCB and H 2 SO 4 ; (e) specific surface area (SSA); (f) point of zero salt effect (PZSE); and (g) surface net charge ( σ ).

The analytical quality program of soil fertility laboratories that adopt the Embrapa methods (PAQLF) is a voluntary national sample-exchange program. PAQLF is managed by Embrapa Solos (National Soil Research Center), and actually is comprised of 82 Brazilian soil fertility laboratories that use P and K extraction with Mehlich-1 solution; Al, Ca, and Mg with KCl solution; soil pH in water; and total organic C by colorimetric or Walkley–Black methods. The quality of soil-test results is evaluated by true values taken as mean (accuracy) following removal of outliners by up to three interactions until CV falls below 20%, and by sample with three replications (precision). Inaccuracy and Imprecision Index are calculated for all laboratories and a ranking is established by an Excellence Index. Yearly the best ranked laboratories are indicated and qualified to use the Quality Control Seal. The objective of this research was to evaluate the performance in regard to accuracy and precision, characterize soil-testing...

Soil solution chemistry is a powerful tool for studying many aspects of soil science. Consequently, isolation and chemical analysis of the soil solution are essential procedures in soil chemistry studies. Among several isolation techniques, centrifugation appears most promising as a method of extracting the soil solution in the laboratory. However, some operational conditions must be defined. The present work reports the influence of the centrifugation time (30 and 60 min) and speed (560, 2,260, and 5,080 g) on the observed composition of the soil solution of four samples from two typical and representative Brazilian Oxisols. The concentrations of {\rm{ NH _{4} ^{ + } }, } Ca, Mg, Al, Na, K, Mn, Fe, Zn, Cl−, {\rm{ NO _{3} ^{ - } }, } {\rm{ SO _{4} ^{2 - } }, } and F− varied significantly with the centrifugation speed but not with time. Charge balance calculations for the evaluation of the electrochemical neutrality showed that an extraction time of 1 h at a speed of 2,260 g should be recommended for furth...

Cesium-137 (137Cs) soil-to-plant transfer factors obtained in an accidentally contaminated Oxisol in Goiânia and another Oxisol experimentally contaminated show that these soils present higher transfer of 137Cs from soil to plants than previously observed in temperate climates. These differences were discussed in the light of the pedology and geochemical partitioning. Some tropical soil characteristics, such as acidity, low availability of nutritive elements and low content of 2:1 clay type may account for the high mobility for 137Cs even after a long period after contamination. Results of sequential extraction showed that most of the 137Cs is bound to soil oxides.

Thirty-two soil samples from different locations of the Rio de Janeiro State, Brazil, were studied in order to evaluate the amount of aluminum (Al) obtained by three extractants (1 M KCl, 1 M NH4OAc, 0.5 M CuCl2) and by the extraction of humic and fulvic acids (0.5 M NaOH, following purification). The results were discussed in relation to statistical correlations with soil organic matter content and soil pH (water). In general, the displacement of Al followed the order: CuCl2 > NH4OAc > KCl > humus extraction. The greater amounts of Al extracted by CuCl2 were attributed mainly to Al from soil organic matter.

As conseqüências da deficiência ou toxidez de micronutrientes na produção agrícola do estado do Rio de Janeiro são pouco conhecidas. Desta forma, em 1997, foram quantificados os teores de cobre, zinco, ferro e manganês em 103 amostras de horizontes superficiais de solos representativos do estado, sendo utilizados os extratores Mehlich-1, DTPA-TEA e HCl 0,1 mol L-1. De maneira geral, o extrator HCl 0,1 mol L-1 foi o que apresentou maior poder de extração dos micronutrientes estudados, tendo o Mehlich-1 extraído as menores quantidades de cobre e ferro e o DTPA-TEA as menores quantidades de zinco e manganês. Segundo os resultados, equações de conversão entre extratores, para um mesmo elemento, e a utilização de faixas de interpretação desenvolvidas para regiões edáficas diferentes das condições do trabalho podem não estimar corretamente a disponibilidade dos micronutrientes às plantas. The consequences of micronutrient deficiency or toxicity for the agricultural productivity in the state of Rio de Janeiro are not adequately known. For this reason, in 1997, the levels of copper, zinc, iron, and manganese were quantified in 103 samples from surface horizons of representative soils of the state. The extractant solutions used were Mehlich-1, DTPA-TEA, and HCl 0.1 mol L-1. In general, the HCl 0.1 mol L-1 solution extracted the highest amounts of the studied micronutrients. Mehlich-1 extracted the smallest amounts of copper and iron, and the DTPA-TEA extracted the smallest amounts of zinc and manganese. The results showed that the use of linear regression equations for conversion of values amongst methods of a specific element and the use of ranges of interpretation developed in different edaphic conditions, in comparison to the present work, are not recommended. They can lead to incorrect diagnoses.

Considering the increasing need for reliable soil carbon (C) and nitrogen (N) determinations, 19 Brazilian soil samples were selected to compare the results of two methods (a) a modified dichromate wet digestion and Kjeldahl that has been in use by Embrapa in most of Brazilian soil surveys (Embrapa's method), and (b) an automated technique based on dry combustion (Perkin-Elmer 2.400 Series II–CHN Mode). Considering that the last method is very much influenced by sample size, two weights were tested (10 and 100 mg). The influence of two particle sizes for both methods (crushed and sieved to pass a 0.177-mm mesh) was also tested. A simple linear regression with the confidence limits for the intercept and slope were used to compare methods. Precision was evaluated by the coefficient of variation (C.V.). The results showed that simple crushing is inadequate for performance analysis by dry combustion mainly for small samples (10 mg), where the precision is also low (19.77% for N and 9.41% for C). The dry combu...

Pesquisas comparativas em fragmentos florestais que visem avaliar o efeito de diferentes impactos antrópicos sobre o solo são praticamente inexistentes. Assim, o objetivo principal deste trabalho foi caracterizar e comparar os horizontes orgânicos do solo em relação a algumas variáveis pedológicas sob mata primária e sob capoeira de idade avançada, com mais de 40 anos, resultado da seleção e extração de indivíduos arbóreos de valor comercial. Para isso, foram estudadas duas áreas de Mata Atlântica da região de Tabuleiros Terciários do norte do Espírito Santo: a Mata Alta, uma mata primária, e a Capoeira de Extração, uma mata secundária. Na Mata Alta, verificou-se débil acumulação orgânica superficial (4,0 t ha-1), devida à rápida decomposição dos aportes orgânicos que caem sobre o solo. O primeiro horizonte do solo caracteriza-se pela presença de um suborizonte de interface com as camadas foliares (A11), mais rico em carbono e nutrientes que o suborizonte A12 subjacente, pela maior saturação por bases (entre 50 e 70%) e por apresentar uma relação C/N menor que 12. Nesta mata, verificou-se a estabilidade sazonal tanto dos estoques orgânicos como dos nutritivos. A Capoeira de Extração apresentou, em relação à mata não perturbada, maior acumulação do estoque superficial de matéria orgânica (5,5 t ha-1, no verão, e 7,5 t ha-1, no inverno), bem como maior conteúdo de carbono e de nutrientes no solo, principalmente no inverno, indicando um bloqueio na decomposição e na ciclagem de nutrientes. A retirada de determinadas espécies arbóreas, em princípio, pode explicar a diferença observada no processo de decomposição e na ciclagem de nutrientes. The main purpose of this work was to evaluate differences in the superficial organic accumulation in soil with regard to some pedological parameters of a secondary forest (older than 40 years) submitted to anthropic intervention, i.e., harvest of economically important tree species. Thus, the present work compares two sites of the "Tabuleiro" Atlantic Forest in northern Espírito Santo: a primary forest, the "Mata Alta", and a secondary forest, the "Capoeira de Extração". The organic matter accumulation below the "Mata Alta" is relatively low (4.0 t ha-1), as a result of the fast decomposition of the foliar debris. Within the A horizon, the base saturation is about 50-70% and the C/N ratio is 12. Its main feature is the presence of an interface horizon between the litter layers and the first hemiorganic horizon (A11), where most of the nutrients and organic matter are concentrated. Here a seasonal stability of the organic matter accumulation was observed. The "Capoeira de Extração" had a higher organic accumulation (5.5 t ha-1 in the summer and 7.5 t ha-1 in the winter), and higher values of carbon and nutrients in soil as compared with the undisturbed forest soil. These results showed an interruption in the decomposition process and the nutrient turnover, which may be related to the harvesting of certain tree species.

A extração da acidez potencial com acetato de cálcio 0,5 mol L-1 é um método amplamente utilizado nos laboratórios de análises de solo no Brasil. Neste trabalho, foram analisadas cento e duas amostras de solos do Estado do Rio de Janeiro, em 1996, visando obter a curva de calibração entre a acidez potencial e o pH de equilíbrio da suspensão de solo com solução-tampão (pH SMP). Os resultados demonstraram que a acidez potencial pode ser estimada por meio da curva de regressão da solução-tampão SMP (R² = 0,90**). Também foi observada correlação significativa entre o pH de equilíbrio da suspensão de acetato de cálcio 0,5 mol L-1 e o pH SMP. The potential extractable acidity method by Ca(OAc)2 0.5 mol L-1 is widely used in Brazilian soil analysis laboratories. To define the calibration curve between potential extractable acidity and buffered pH SMP, 102 samples of soils from Rio de Janeiro State, Brazil, were analyzed in 1996. The data showed that potential acidity can be estimated by pH SMP buffer suspension (R² = 0.90**) and that the pH of Ca(OAc)2 0.5 mol L-1 suspension was significantly correlated with the pH SMP.

A matéria orgânica do solo é parte de um sistema dinâmico influenciado por vários fatores, incluindo clima, conteúdo e natureza das argilas, uso da terra, sistemas de manejo e drenagem, os quais afetam as taxas de adição e os processos de transformações e evolução dos compostos orgânicos. O objetivo deste trabalho foi quantificar e avaliar a distribuição das frações húmicas em Organossolos de diferentes ambientes e regiões do Brasil, relacionando-os com os processos de subsidência. O teor de carbono (C) nas substâncias húmicas indicou predomínio do C da fração ácido húmico (C-FAH de 22,1 g kg-1 a 153,7 g kg-1) nos solos de regiões altimontanas e ambientes de planalto. Possivelmente, o clima mais frio, aliado a uma melhor fertilidade, favoreceu a formação desta fração em detrimento das frações ácido fúlvico e humina. Por outro lado, o maior teor de ácidos húmicos torna os Organossolos nesses ambientes mais susceptíveis aos processos de subsidência, principalmente quando manejados para agricultura. Já nos ambientes de várzeas e de planícies litorâneas, houve maior formação do C da fração humina (C-HUM de 79,2 a 267,2 g kg-1), que é a fração das substâncias húmicas mais resistente à decomposição. O somatório das frações húmicas representou 89% do carbono total, estando essas duas variáveis altamente correlacionadas. A relação Extrato alcalino humina (EA/HUM) agrupou classes de Organossolos pelo ambiente de formação, sendo sugerida como atributo diagnóstico nos níveis inferiores do Sistema Brasileiro de Classificação de Solos (SiBCS), possibilitando diferenciar os Organossolos quanto ao potencial de subsidência. ABSTRACT The organic matter of soil is part of a dynamic system influenced by several factors, including climate, the content and nature of clays, land use, management and drainage systems, all of which affect the addition rates, and the processes of transformation and evolution of organic compounds. The objective of this study was to quantify and assess the distribution of humic fractions in histosols in different environments and regions of Brazil, relating them to the processes of subsidence. The carbon (C) content in humic substances indicated a predominance of C from the humic-acid fraction (HAF-C of 22.1g kg-1 to 153.7g kg-1) in soils from high altitude mountainous regions and upland areas. Possibly the colder climate, coupled with improved fertility, favored the formation of this fraction at the expense of the fulvic acid and humin fractions. On the other hand, the higher humic-acid content makes organosols in these environments more susceptible to the processes of subsidence, especially when under agricultural management. Whereas in flood and coastal-plain environments, there was a greater formation of C from the humin fraction (HUM-C from 79.2 to 267.2g kg-1), being the fraction of humic substances most resistant to decomposition. The sum of the humic fractions represented 89% of the total carbon, these two variables being highly correlated. The relationship between alkaline extract and humin (AE / HUM) groups classes of histosols by their formation environment, and is suggested as a diagnostic attribute at the lower levels of the Brazilian System for Soil Classification (SiBCS), allowing differentiation of the histosols as to their potential for subsidence.

Os Organossolos são formados em condições geomórficas e climáticas que favorecem o acúmulo de material orgânico e sua drenagem para uso agrícola conduz a subsidência e modificações no teor de matéria orgânica do solo (MOS), com implicações na sustentabilidade desses solos. O objetivo deste trabalho foi avaliar alguns atributos físicos e sua relação com o teor e grau de decomposição da matéria orgânica de Organossolos Háplicos formados em ambientes hidromórficos, nos Estados do Rio de Janeiro (clima tropical atlântico Aw), Maranhão (tropical Awh) e Paraná (subtropical Cfb), com distintos usos. Foram utilizados os métodos recomendados no Sistema Brasileiro de Classificação de Solos (SiBCS) para caracterização de oito perfis, totalizando 30 horizontes, de Organossolos, sendo o teor de matéria orgânica quantificado pelo método da mufla. Os atributos físicos densidade do solo (Ds), densidade da matéria orgânica (DMO), percentual de material mineral (MM) e resíduo mínimo (RM) refletiram no teor e grau de transformação do material orgânico. A Ds variou de 0,09 a 0,93 Mg m-3, com média de 0,44 Mg m-3 e a DMO, de 0,02 a 0,66 Mg m-3, sendo a média de 0,28 Mg m-3. Observou-se relação diretamente proporcional entre a Ds e os atributos MM e RM. Quanto ao grau de decomposição, os materiais orgânicos foram identificados principalmente nas classes de hêmicos e sápricos; porém, como classes distintas foram obtidas em função do método usado, recomenda-se o uso do índice de pirofosfato e teor de fibras esfregadas em conjunto, definindo as classes por faixa de valores. Os Organossolos com menor alteração antrópica, no Estado do Rio de Janeiro (RJ02 e RJ08), apresentaram os maiores teores de matéria orgânica e os menores valores de Ds, DMO e MM. Assim, esses atributos são relevantes como indicadores do potencial de subsidência e da degradação dos Organossolos, solos relevantes pelo seu alto estoque de carbono e para a preservação de aquíferos. Histosols are formed under geomorphic and climate conditions that allow the accumulation of organic material, and their drainage for agriculture leads to the subsidence process and changes in the content of soil organic matter (SOM), with implications in the sustainability of these soils. The objective of this study was to evaluate some physical properties of Histosols and their relationship to SOM content and degree of decomposition in soils formed under hydromorphic conditions in the states of Rio de Janeiro (Aw tropical Atlantic), Maranhão (Awh tropical), and Parana (Cfb subtropical), with different usages. The methods recommended by the Brazilian Soil Classification System (SiBCS) were applied for characterization of the eight profiles, totaling 30 horizons; the organic matter content was quantified using a muffle furnace. The physical properties, soil bulk density (BD), organic matter density (OMD), percentage of mineral material (MM), and minimum residue (MR), reflected the content and transformation degree of the organic matter. The BD values varied from 0.09 to 0.93 Mg m-3, with an average of 0.44 Mg m-3 and OMD varied from 0.02 to 0.66 Mg m-3, with an average of 0.28 Mg m-3. A directly proportional relationship between BD and the properties MM and MR was observed. In the classification of the decomposition degree, the organic materials were identified mainly as hemic and sapric. Since different classes were obtained according to the method applied, it is recommended the combined usage of the pyrophosphate index and the content of rubbed fibers, defining the classes according to a range of values. In the Histosols with less anthropic alteration, in the State of Rio de Janeiro (profiles RJ02 and RJ08), the levels of organic matter were highest and the values of BD, OMD, and MM lowest. Thus, these properties are relevant to indicate the potential of subsidence and degradation in Histosols, an important soil class with regard to carbon storage and preservation of aquifers.

The variety of soils in the State of Acre is wide and their chemical profiles are still not fully understood. The nature of the material of origin of these soils is indicated by the high aluminium (Al) content, commonly associated with high calcium (Ca) and magnesium (Mg) contents. The study objective was to use different methods to quantify Al in soils from toposequences formed from material of a sedimentary nature originating from the Solimões Formation, in Acre, Brazil. Trenches were opened at three distinct points in the landscape: shoulder, backslope and footslope positions. Soil samples were collected for physical, chemical, mineralogical analyses. The Al content was quantified using different methods. High Al contents were found in most of these horizons, associated with high Ca and Mg levels, representing the predominant cations in the sum of exchangeable bases. The mineralogy indicates that the soils are still in a low weathering phase, with the presence of significant quantities of 2:1 minerals. Similar Al contents were determined by the methods of NaOH titration, xylenol orange spectrometry and inductively coupled plasma optical emission spectrometry. However, no consistent data were obtained by the pyrocatechol violet method. Extraction with KCl overestimated the exchangeable Al content due to its ability to extract the non-exchangeable Al present in the smectite interlayers. It was observed that high Al contents are related to the instability of the hydroxyl-Al smectite interlayers. Há grande variedade de solos no Acre cujos perfis químicos não são ainda totalmente compreendidos. A natureza do material de origem desses solos pode ser observada a partir do magnésio (Mg). O objetivo deste estudo foi utilizar diferentes métodos para quantificar o alumínio em solos de topossequências formadas, a partir de um material de natureza sedimentar proveniente da Formação Solimões, Estado do Acre. Foram abertas trincheiras em três pontos distintos: terço superior (P1), terço médio (P2) e terço inferior (P3) da elevação. As amostras de solo foram coletadas para a realização de análises física, química e mineralógica e caracterização do teor de Al. A mineralogia da fração argila foi identificada e o teor de alumínio, quantificado, utilizando diferentes métodos. Na maioria dos horizontes, foram encontrados altos teores de Al, associados a elevados teores de Ca e Mg, os cátions predominantes na soma de bases trocáveis. A mineralogia indica que os solos estão ainda numa fase de baixo intemperismo, com a presença de quantidades significativas de minerais 2:1. O teor de Al determinado pelos métodos de titulação com NaOH, alaranjado de xilenol e espectrometria de plasma, indutivamente acoplado à espectrometria de emissão óptica, foram semelhantes. No entanto, o método de violeta de pirocatecol não apresentou dados consistentes. A extração com KCl superestimou os teores de Al trocável, em razão da sua capacidade de extrair o Al presente em formas não trocáveis nas intercamadas das esmectitas. Observou-se que o teor de Al elevado está relacionado com a instabilidade das intercamadas das esmectitas hidroxil-Al. Made available in DSpace on 2020-10-21T09:12:16Z (GMT). No. of bitstreams: 1 Bernini-et-al.-2013-V37N6a15.pdf: 642841 bytes, checksum: 0a302018157c7d6e442bbe9847101a70 (MD5) Previous issue date: 2013

A produtividade dos pomares de cupuaçu na Amazônia tem experimentado lento declínio, provavelmente devido à diminuição da fertilidade do solo, requerendo adubações. Na ausência de recomendações técnicas para quantificar a demanda por nutrientes por essa cultura, o uso do Sistema Integrado de Diagnose e Recomendação (DRIS) pode representar uma alternativa para suprir essa necessidade. O objetivo deste trabalho foi avaliar os diagnósticos produzidos por diferentes fórmulas e critérios de interpretação dos índices DRIS em pomares de cupuaçu. Amostras foliares de 153 pomares foram analisadas para os nutrientes N, P, K, Ca, Mg, Zn, Mn, Cu e Fe e diagnosticadas por três fórmulas DRIS: Beaufils, Jones e Wadt e colaboradores. Na interpretação dos índices DRIS, utilizaram-se: o método DRIS Matéria Seca (M-DRIS), que separa os nutrientes em limitantes ou não limitantes, e o método do Potencial de Resposta à Adubação, o qual separa os nutrientes no estado nutricional de insuficientes, equilibrados ou em excesso. Foram também adotados níveis críticos para os teores dos nutrientes foliares em cupuaçueiros, oriundos da literatura. Os diagnósticos produzidos pelos diferentes critérios de interpretação dos índices DRIS não foram consistentes entre si ou em comparação com o método do nível crítico. A exceção foi a fórmula de Wadt e colaboradores que mostrou maior consistência entre os diagnósticos, independentemente do critério utilizado para sua interpretação. Os valores sugeridos para avaliação do estado nutricional pelo método do nível crítico não foram satisfatórios. The productivity of cupuassu orchards in the Amazon region has been gradually declining, probably due to the reduction in soil fertility, calling for fertilization. In the absence of technical recommendations to calculate the nutrient demand of an orchard, the use of the Integrated Diagnosis and Recommendation (DRIS) may represent an alternative to fill this gap. The purpose of this study was to evaluate the diagnoses based on different formulas and criteria of interpretation of DRIS indices of cupuassu orchards. The contents of N, P, K, Ca, Mg, Zn, Mn, Cu, and Fe were determined in leaf samples from 153 orchards and diagnosed by three DRIS formulas: Beaufils, Jones and Wadt and coleagues. The DRIS indices were interpreted by: DRIS including dry matter (M-DRIS), which separates the nutrients in limiting or non-limiting, and the method of the response potential to fertilization, which classifies the nutritional status of elements in insufficient, balanced or excess. Critical levels of foliar nutrients were also adopted for cupuassu trees from the literature. The diagnoses based on the different interpretation criteria of the DRIS indices were not consistent with each other or with the threshold method, except for the formula Wadt and coleagues. The diagnoses by the Wadt and coleagues formula were more consistent, regardless of the criteria used for interpretation. The suggested values to assess the nutritional status by the threshold method were not satisfactory.

A dinâmica e os atributos da matéria orgânica do solo (MOS) há muito vêm sendo estudados em solos minerais. Entretanto, em condições tropicais, poucos estudos envolvem os solos orgânicos e a caracterização das substâncias húmicas (SH), ou sua relação com atributos químicos relevantes, para avaliar o potencial agrícola. Os objetivos deste estudo foram: avaliar atributos químicos de Organossolos Háplicos de diferentes regiões do Brasil; quantificar o teor de C orgânico no solo e nas frações da MOS; e avaliar as relações entre esses atributos em cada ambiente de formação. Foram avaliados os atributos químicos e quantificados os teores de C orgânico total e das frações da MOS (ácido fúlvico - C-FAF, ácido húmico - C-FAH e humina - C-HUM), bem como as relações C-FAH/C-FAF, C-EA/C-HUM, em que C-EA (carbono do extrato alcalino) é obtido pelo somatório de C-FAF e C-FAH. Os Organossolos apresentaram elevada acidez, saturação por bases abaixo de 50 % e elevada capacidade de troca catiônica potencial (T), embora com valores altos de Ca2+ e Mg2+ e de soma de bases, na maioria dos perfis. Os teores de C nas frações húmicas apresentaram correlação significativa com diferentes atributos dos solos, como entre os valores de C-FAH e de C-HUM e os teores de N, H+ e T. O C-HUM e o C-FAH predominaram sobre o C-FAF. A relação C-FAH/C-FAF foi menor nos horizontes mais superficiais, dos perfis com maior intensidade de uso ou efeito de queimadas, assim como os teores de matéria orgânica, C-HUM e C-FAH. Os atributos químicos e os teores de C nas substâncias húmicas refletiram o grau de transformação da MOS e alterações pelo uso agrícola, indicando a vulnerabilidade dos Organossolos. The dynamics and properties of soil organic matter (SOM) in mineral soils have been studied for many years. However, under tropical conditions, few studies involve organic soils, the characterization of humic substances (HS), or their relationship with chemical properties related to the agricultural potential of Histosols. The objectives of this study were to characterize chemical properties of Histosols in different Brazilian regions; to quantify soil organic carbon and carbon in the SOM fractions; and to evaluate possible relationships between organic carbon content and soil chemical properties in each environment. The chemical properties were measured and carbon was quantified in the soil samples and the SOM fractions (fulvic acid - C-FAF, humic acid - C-HAF, humin - C-HUM). The ratios C-HAF/C-FAF, C-EA/C-HUM, where C-EA (carbon of the alkaline extract) is equal to the sum of C-FAF+C-HAF, were also evaluated. The acidity of the Histosols was high, base saturation below 50 %, and the cation exchange capacity (CEC) high, although the Ca and Mg levels and sum of bases were high in most profiles. The humic fractions were significantly correlated with different soil properties, such as C-HAF and also C-HUM with N, H+, and CEC. The C-HUM and C-HAF predominated over C-FAF. The C-HAF/C-FAF ratio was reduced in the surface layer of Histosols under intense agricultural use or frequent vegetation burning; the SOM, C-HUM and C-HAF contents were also reduced. The chemical properties and C content in the humic substances reflected the transformation degree of SOM and the changes caused by agricultural use, indicating the vulnerability of Histosols.

Exchangeable Al has been used as a criterion for the calculation of lime requirement in several Brazilian States. However, the laboratory method with extraction by a 1 mol L-1 KCl solution followed by indirect alkaline titration is not accurate for some Brazilian soils, mainly in the case of soils with high organic matter content. The objective of this study was therefore to evaluate the stoichiometry of H+/Al3+ in KCl soil extracts. The results suggested that organically complexed Al is the main contributor to exchangeable acidity in soils enriched with organic matter. Liming recommendations for organic soils based exclusively on exchangeable Al determined by the NaOH titration method should therefore be revised. A determinação de alumínio trocável é utilizada como critério para cálculo de calagem em vários estados brasileiros. Contudo, a determinação indireta pela titulação com NaOH, após extração com solução de KCl 1 mol L-1, pode não ser adequada para certos tipos de solos brasileiros, notadamente aqueles que apresentem altos teores de carbono orgânico. Dessa forma, o principal objetivo deste trabalho foi avaliar a estequiometria da relação H+/Al3+ em extratos de KCl. Os resultados obtidos sugerem que o Al complexado pela matéria orgânica, em solos orgânicos, é o principal contribuinte para a acidez trocável obtida por titulação. Dessa forma, a recomendação de calagem em solos orgânicos baseado somente na determinação de alumínio trocável por titulação com NaOH deve ser revista. Made available in DSpace on 2018-10-24T00:32:55Z (GMT). No. of bitstreams: 1 DanielV33n4a31.pdf: 1298387 bytes, checksum: 123805ed94bd03a131181ad08cff490f (MD5) Previous issue date: 2010-01-25

Objetivou-se neste trabalho caracterizar e classificar quatro Plintossolos localizados no município de Pinheiro-MA, de forma a validar novas classes propostas no Sistema Brasileiro de Classificação de Solos (SiBCS). Foram selecionados quatro pedons em pontos distintos da paisagem: terço superior, médio, inferior e base da encosta, tendo como material de origem arenitos ferruginosos da Formação Itapecuru e sedimentos coluviais e aluviais. Os perfis foram morfologicamente descritos e os horizontes avaliados quanto às propriedades físicas, químicas e mineralógicas. Os três perfis localizados ao longo da encosta foram classificados como Plintossolos Argilúvicos, e o situado na transição para a várzea, como Plintossolo Háplico. Três perfis apresentaram caráter concrecionário no perfil de solo, identificando os solos como petroplínticos no quarto nível categórico. Todos os solos apresentaram caráter alítico, indicando ambiente de formação de solos diferenciado nesta localidade do Estado do Maranhão, que favorece a preservação de argilominerais de alta atividade juntamente com elevada acidez do solo. As classes inseridas no SiBCS, na ordem dos Plintossolos, se mostraram adequadas para classificar os perfis e contemplam as variações relacionadas ao ambiente pedogenético. The objective of the study was to characterize and classify four Plintosols (Ultisols and Entisols with plinthite) in Pinheiro county, Maranhão state (Brazil), to validate the new classes proposed in the Brazilian System of Soil Classification (SiBCS). Four pedons were selected in different hill slope positions: shoulder, backslope, footslope, and toeslope. The parent material consisted of ferruginous sandstone of the Itapecuru Formation and colluvial and alluvial sediments. Soil profiles were morphologically described and each horizon analyzed for physical, chemical and mineralogical properties. According to the SiBCS, the three soil profiles along the slope were classified as Plintossolos Argilúvicos (Plinthudults), and the profile in the transition to lowland as Plintossolo Háplico (Entisols). Three profiles had a concretionary character and were classified as petroplinthic in the subgroup level. All soils had an alitic character, indicating that the soil formation environment in Maranhão state favors the preservation of clay minerals with high activity associated with high soil acidity. The soil classes introduced in the SiBCS to complement the Plintosols order proved adequate to classify the profiles and take into account the variations related to the pedogenetic environment.

Desde 1986, vem-se observando o fenômeno de repelência à água, em amostras de horizontes coletadas para levantamentos de solos realizados pelo Departamento de Solos da Universidade Federal Rural do Rio de Janeiro (UFRRJ) e pela EMBRAPA - Centro Nacional de Pesquisa de Solos. Com o objetivo de estudar as causas desse fenômeno, selecionaram-se sete amostras de solo que, inicialmente, foram submetidas à avaliação do grau de repelência à água pelos métodos da molaridade de gotas de etanol e tempo de penetração de gotas de água no laboratório de solos da UFRRJ. A fim de identificar os compostos orgânicos responsáveis pelo fenômeno da repelência, foram empregados dois métodos de extração, os quais foram eficientes na retirada do caráter hidrofóbico das amostras. O primeiro teve por base o uso da partição isopropanol:água destilada, e o outro, desenvolvido pelos autores, empregou extrações simples com n-hexano, éter de petróleo e clorofórmio, além de partições n-hexano:água destilada e clorofórmio:água destilada. As substâncias extraídas foram analisadas no Instituto de Biociências da Universidade de São Paulo (USP). Os resultados indicam que as substâncias isoladas têm sua origem na vegetação local, sendo os alcanos de alto peso molecular os responsáveis pelo caráter hidrofóbico das amostras de solo. Made available in DSpace on 2020-01-07T18:08:38Z (GMT). No. of bitstreams: 1 IDENTIFICACAOECARACTERIZACAO1998.pdf: 95824 bytes, checksum: 400514b4176c8d08a9850d7f0556149d (MD5) Previous issue date: 1998