Luciano Pasqualoto Canellas

Organic matter Fractions in a toposequence of six soils in the state of Rio de Janeiro, Brazil

The influence of topographical position on organic matter fractions was studied in tropical soil toposequence in the campus of Universidade Federal Rural do Rio de Janeiro, State of Rio de Janeiro, Brazil. Six soil profiles were selected for the study, two at the shoulder position (Typic Kannapludalf, profiles 1 and 2), one on backslope (Typic Kannapludalf, profile 3), two on footslope (Fragiaquult, profiles 4 and 5) and one on the tooslope position (Mollic endoaquent, profile 6). These soils have lower content of organic carbon. The main organic fractions modified through all water flux in the toposequence were free fulvic acids and fulvic acids. Organic matter was correlated with soil properties, namely soil color, bulk soil density, total porosity, Ca2+, K+, Na+ and H+ content, and CEC. At the slope position, the major pathway of organic matter humification was the herance pathway.

Avaliação de características de ácidos húmicos de resíduos de origem urbana: I. métodos espectroscópicos (UV-Vis, IV, RMN 13C-CP/MAS) e microscopia eletrônica de varredura

Physico-chemical characteristics of humic acids obtained from urban waste (AH-CRSU) and sewage (AH-LETE) produced in the city of Rio de Janeiro, were determined through elemental analysis, total acidity, spectroscopic methods and electron scanning microscopy. The analysis of structural traits revealed some differences between the humic acids investigated. The presence of aromatic moieties was confirmed with UV-Vis spectroscopy, with more substituted systems present in the AH-LETE. IR spectroscopy showed aliphatic groups in the AH and as more complex signals due the presence of polysaccharides in AH-CRSU. Furthermore, the presence of COOH, COO-, CO2NH2, OH, was observed apart from aromatic systems. The CP/MAS 13C NMR analysis allowed to observed a higher amount of aromatic and COOH groups. showed the presence of polysaccharides, aminoacid N and OCH3 groups. The results allow to define the humic acids from urban source as of the type or like those of pedogenic origin.

Adsorção de cu2+ e cd2+ em ácidos húmicos extraídos de resíduos orgânicos de origem urbana

Copper and cadmium adsorption by humic acids extracted from compost of municipal waste (AH-CRU) and sewage sludge (AH-LETE) was studied by adsorption isoterms at pH 5,5. High adsorption capacity by humic substances was verified and copper adsortion followed the Langmuirx92s model. The maximum copper adsorption was 55.5g of Cu2+kg-1 of AH-LETE and 45,9g Cu2+kg-1 of AH-CRU. The best model for cadmium adsorption was the Freundlichx92s model, and different sites of adsorption were observed by infrared spectroscopy. The main adsorption sites observed were COO-, OH and N-H.

Efeito de práticas de manejo sobre o rendimento de grãos e a qualidade industrial dos grãos em arroz irrigado

The purpose of the research was to study the use of liming, seeding density of two paddy rice cultivars and harvest time with rice yield and mill quality. The experiment was carried out during 1993/94 growing season in Casemiro de Abreu (RJ), Brazil. The two rice cultivars used were BR-IRGA 409 and BR-IRGA 412, two of limestone doses (0 and 200kg ha-1) and three seeding densities (100, 200 and 300kg ha-1) were distributed in a completely randomized block design. The use of liming and variation of seeding density did not affect rice quality. The moisture content of the rice grains that resulted in highest quality at harvest was between 17,5-22%.

Initial performance of pineapple and utilization of rock phosphate applied in combination with organic compounds to leaf axils

Rock phosphates have low solubility in water, but good solubility in acid. The use of or ganic compounds together with these phosphorus sources applied to the basal leaf axils of pineapple can increase the solubility of this phosfate source and increase the P availability to the crop. A greenhouse experiment was conducted using Araxa rock phosphate (10 g) in combination or not with solutions containing increasing concentrations of humic acids (0 to 40 mmol L -1 of carbon), with or without citric acid (0.005 mmol L -1 ), applied to basal leaf axils of pineapple cv. Perola. Growth and nutritional characteristics of aerial plant parts were assessed. Growth rates of aerial parts and N, P , K, Ca and Mg contents increased curvilinearly with increasing concentration of carbon in the form of humic acids. Maximum values were found for the concentration of 9.3 mmol L -1 of carbon combined with 0.005 mmol L -1 of citric acid and natural phosphate.

Initial growth of maize in response to application of rock phosphate, vermicompost and endophytic bacteria

Devido a alta exigencia energetica e demanda por recursos nao renovaveis para a producao de fertilizantes quimicos, somadas, ainda, ao impacto ambiental provocado pelo uso de tais produtos, e importante a intensificacao de pesquisas com insumos agricolas de base biologica. O uso de bacterias endofiticas fixadoras de nitrogenio e solubilizadoras de fosfatos pode disponibilizar esses nutrientes para as plantas a partir do ar e de fontes fosfatadas pouco soluveis, como fosfatos de rochas. O objetivo deste trabalho foi avaliar a nutricao e o crescimento inicial de milho (Zea mays L.) em resposta a inoculacao de bacterias endofiticas fixadoras de nitrogenio e solubilizadoras de fosfato de rocha, em formulacao simples ou mista, aplicadas com vermicomposto. As plantas de milho dos tratamentos contendo bacterias, tanto as diazotroficas quanto as solubilizadoras de fosfato, quando comparadas as do controle, apresentaram maiores teores foliares de nitrogenio e fosforo no milho, acompanhados por caracteristicas de crescimento mais elevadas. A aplicacao de vermicomposto apresentou efeito sinergico quando combinada com as bacterias endofiticas. Dessa forma, a inovacao da combinacao dos fatores estudados pode contribuir para o desenvolvimento inicial do milho.

Aumento da resolução de espectros de RMN 13C de ácidos húmicos em solução através do tratamento prévio com KCl 0,03 mol L-1

High levels of Fe and Mn present in some soils and compost organic matter decrease the resolution of 13C NMR spectra of humic substances. Addition of KCl up to a concentration of 0,03 mol L-1 to humic substances extracts followed by centrifugation is an efficient method of eliminating clays and minerals containing high levels of paramagnetic metals such as Fe and Mn thus increasing the resolution of 13C NMR spectra.

Avaliação de características dos ácidos húmicos de resíduos de origem urbana: II. métodos termodegradativos (pirólise acoplada à cromatografia gasosa / espectrometria de massa)

This research was conducted to investigate the principal structural units from humic acids obtained from urban waste compost (AH-CRSU) and sewage sludge (AH-LETE) by pyrolysis - gas chromatography / mass spectrometry. The humic acids from sewage sludge presented most mono and diaryl esters with higher mass. The n-alcans in AH-LETE showed a shorter chain than AH-CRSU. Phthalate fragments were incorporated into the humic acid structures, probably due to an organic matter contamination by plastics. The aromatic compounds in the AH-LETE originated mainly from naphtalene derivatives and benzene derivatives with alquil chain substitutives higher than AH-CRSU. The nitrogenated compounds were essentially heteroaromatic and the oxigenated compounds were substituted furans originated from carbohydrate degradation. The oxiaromatic compounds were substituted phenols.

Structural features of humic acids isolated from soils amended with urban organic residues: an elemental composition, 13C NMR and Py-GC/MS analysis

The structural features of humic acids (HA) after addition of organic matter from urban residues were evaluated. The HAs were extracted from the surface (0-20 cm) of an ultisol (Seropedica, RJ) and oxisol (Pirai, RJ) which had been treated with the equivalent of 80 t ha-1 (dry material) of compost from urban waste and also sewage sludge. The incubation time in the laboratory was 24 weeks under room temperature and humidity at field capacity. Tha HAs were characterized by elemental analysis, 13C NMR spectroscopy and pyrolysis coupled to gas chromatography/mass spectrometry (Py-GC/MS). NMR spectroscopy allowed the clear observation of alterations in the molecular composition of the HAs, mainly through the increase in the content of mono and dioxygenated carbon atoms (δ 50-100) and decrease in the content of CH2 and CH3 groups (δ 0-40). The increase in the amount of carbohydrates suggests the presence of more labile structures in the HAs with organic residues amendment. In addition, Py-GC/MS led to the observation of significant qualitative differences between the compounds which arose from the thermal fragmentation of HAs, mainly lipids and carbohydrate derivatives (such as furan), for soil samples treated with either organic residues. The coupling of 13C NMR spectroscopy and Py-GC/MS has proven useful in evaluating physical changes in HAs isolated from soils treated with urban organic residues.