Humic Acids
Mostrando 13-24 de 136 artigos, teses e dissertações.
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13. Estudio teorico de las interacciones de dos modelos de ácidos húmicos con los cationes Al3+, Ca2+, Mg2+, Zn2+, K+ y NH4+ a un nivel de calculo DFT y un modelo de solvatación PCM
In this paper, two models of humic acids, the Temple-Northeastern-Birmingham (TNB) and Kolla models, were studied. Also, the complexation reaction of the structures formed by the interaction of the TNB and Kolla models with Al3+, Ca2+, Mg2+, Zn2+, K+ and NH4+ cations, common in agricultural soils, was studied. These calculations were made for the complexes,
Quím. Nova. Publicado em: 2017-04
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14. Humic substances and its distribution in coffee crop under cover crops and weed control methods
ABSTRACT Humic substances (HS) comprise the passive element in soil organic matter (SOM), and represent one of the soil carbon pools which may be altered by different cover crops and weed control methods. This study aimed to assess HS distribution and characteristics in an experimental coffee crop area subjected to cover crops and cultural, mechanical, and c
Sci. agric. (Piracicaba, Braz.). Publicado em: 2016-08
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15. Solubility of Heavy Metals/Metalloid on Multi-Metal Contaminated Soil Samples from a Gold Ore Processing Area: Effects of Humic Substances
ABSTRACT Bioavailability of heavy metals at contaminated sites is largely controlled by the physicochemical properties of the environmental media such as dissolved organic matter, hydroxides and clay colloids, pH, soil cation exchange capacity and oxidation-reduction potential. The aim of this study was to investigate soil pH and heavy metal solubility effec
Rev. Bras. Ciênc. Solo. Publicado em: 30/06/2016
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16. Plant biostimulants: physiological responses induced by protein hydrolyzed-based products and humic substances in plant metabolism
ABSTRACT In recent years, the use of biostimulants in sustainable agriculture has been growing. Biostimulants can be obtained from different organic materials and include humic substances (HS), complex organic materials, beneficial chemical elements, peptides and amino acids, inorganic salts, seaweed extracts, chitin and chitosan derivatives, antitranspirant
Sci. agric. (Piracicaba, Braz.). Publicado em: 2016-02
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17. Water-Stable Aggregates and Associated Carbon in a Subtropical Rice Soil Under Variable Tillage
ABSTRACT Tillage systems can influence C sequestration by changing aggregate formation and C distribution within the aggregate. This study was undertaken to explore the impact of no-tillage without straw (NT-S) and with straw (NT+S), and moldboard plow without straw (MP-S) and with straw (MP+S), on soil aggregation and aggregate-associated C after six years
Rev. Bras. Ciênc. Solo. Publicado em: 2016
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18. Carbon in Humic Fractions of Organic Matter in Soil Treated with Organic Composts under Mango Cultivation
ABSTRACT Soil organic matter (SOM) plays a key role in maintaining the productivity of tropical soils, providing energy and substrate for the biological activity and modifying the physical and chemical characteristics that ensure the maintenance of soil quality and the sustainability of ecosystems. This study assessed the medium-term effect (six years) of th
Rev. Bras. Ciênc. Solo. Publicado em: 2016
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19. Structure of Humic Substances from Some Regions of the Amazon Assessed Coupling 3D Fluorescence Spectroscopy and CP/PARAFAC
The Amazon rainforest presents one of the greater biodiversity in the world and a huge and dynamic carbon reservoir, both in the vegetation and in the soil pools, so it is an attractive subject of study. In the present paper, humic acids from a toposequence of an Oxisol-Spodosol system associated with kaolin was studied using fluorescence emission-excitation
J. Braz. Chem. Soc.. Publicado em: 2015-06
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20. Enraizamento adventício de justícia vermelha e sanquésia usando ácidos indolbutírico e húmico
Plant regulators, as well as bioactive fractions of the organic matter, can accelerate the development and increase the efficiency of adventitious rooting in ornamental plants. We evaluated rooting in the Brazilian red-cloak (Megaskepasma erythrochlamys) and sanchezia (Sanchezia nobilis) cuttings in response to application of indole-butyric acid (IBA) and hu
Hortic. Bras.. Publicado em: 2014-12
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21. Humic fractions of forest, pasture and maize crop soils resulting from microbial activity
Humic substances result from the degradation of biopolymers of organic residues in the soil due to microbial activity. The objective of this study was to evaluate the influence of three different ecosystems: forest, pasture and maize crop on the formation of soil humic substances relating to their biological and chemical attributes. Microbial biomass carbon
Braz. J. Microbiol.. Publicado em: 2014-09
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22. Production of humic substances through coal-solubilizing bacteria
In this paper, the production of humic substances (HS) through the bacterial solubilization of low rank coal (LRC) was evaluated. The evaluation was carried out by 19 bacterial strains isolated in microenvironments with high contents of coal wastes. The biotransformed LRC and the HS produced were quantified in vitro in a liquid growth medium. The humic acids
Braz. J. Microbiol.. Publicado em: 2014-09
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23. Aumento del contenido de ácidos húmicos en un carbón de bajo rango a través de la oxidación con aire y con peróxido de hidrogeno o ácido nítrico
Low-rank coals are an important source of humic acids, which are important in retention processes of water and nutrients in plants. In this study coal samples of Montelibano, Colombia, were oxidized with air at different temperatures and subsequently with H2O2 and HNO3. The materials were characterized by FTIR, proximate and elemental analysis, and quantific
Quím. Nova. Publicado em: 2013
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24. Fósforo em cronossequência de cana-de-açúcar queimada no cerrado goiano: análise de ácidos húmicos por RMN de 31P
The aim of this study was to identify, with the use of 31P NMR spectroscopy, organic P species in humic acids (HA) in samples from Oxisol cultivated in chronosequence with sugar cane, pasture and Cerrado. The main forms of P-type found were orthophosphate, monoester-P (phosphate sugars) and P-diester (orthophosphate). The 31P NMR technique proved capable of
Quím. Nova. Publicado em: 2013