Avaliação do potencial de extração de nutrientes por cultivares de milheto para uso no plantio direto.

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Comportamento de variedades de milheto (Pennisetum glaucum (L.) R. Br.) para produção de massa.

- NETTO, D.A.M

Dynamic of polycyclic aromatic hydrocarbons in soils treated with biochar.

In recent years the interest in pyrogenic carbon for agricultural use (biochar, i.e. carbonized biomass for agricultural use) has sharply increased. However biochar contain dangerous compounds such as Polycyclic Aromatic Hydrocarbons (PAHs), many of them potentially carcinogenic and mutagenic. They are organic compounds formed from incomplete combustion of organic materials and are persistent pollutants. Therefore, PAHs concentrations and their dynamic must be evaluated in soils amended with biochar. For this, soil samples were collected in three experimental areas in different years (1, 3, 5 or 6) after the application of 0 (control) or 16 Mg ha-1 of biochar. This is the first report of PAHs persistence up to six years in soil treated with biochar. The biochar application increased total PAHs concentrations up to five years after the application, however the levels have always been an order of magnitude lower the limits of prevention established by International Environmental Agencies for soils. Thus, under the evaluated conditions ,the use of biochar was safe concerning PAHs contamination, besides, after six years of the application, the levels found were similar to the control treatment, making it possible to define a safe frequency of application based on the persistence of PAHs in soil

Synthesis and application of molecularly imprinted polymers for the extraction of caffeine from food and beverage samples / Síntese e aplicação de polímeros com impressão molecular para a extracção de cafeína de amostras de alimentos e bebidas

In this present study molecularly imprinted polymers were synthesized and characterized in order to extract caffeine from different food and beverage samples. The characteristics of molecular recognition of these polymers were used to develop a MIP-SPE methodology, a pre treatment able to eliminate interferences. The accuracy of the proposed method reached 96,4 ± 4,7% and the intermediate precision 2.30%. MIP-SPE cartridges here produced can be reused for at least 3 cycles, being much more affordable than the traditional commercial SPE cartridges. Caffeine was analyzed in fifteen food and beverage samples by the here developed method. It is particularly interesting to emphasize that the analyses of soft drinks and coffee powder samples made it possible to attest that, for this sort of samples, the proposed method is able to completely eliminate all the interferences present in these matrices, being unnecessary to apply chromatographic separation previously to analyte quantification. This result assures the method's selectivity and turns its application to these samples much faster, environmentally friendly and economically affordable. There are other works in literature that propose the use of MIP-SPE to perform caffeine determination in some food and beverage samples, but none of them reaches good accuracy and precision. Also, none of them presented selectivity enough not to need the use of chromatographic separation.  

Semillas de Brachiaria ruziziensis en diferentes tiempos y niveles de mezcla con urea para la formación de pasto.

El cultivo de brachiaria se ha utilizado ampliamente para la implantación de áreas de pasto en sistemas integrados, utilizando fertilización con nitrógeno retardada bajo cubierta para la siembra de maíz. Sin embargo, la mezcla de fertilizantes como la urea promueve una disminución en la calidad fisiológica de la semilla con el tiempo de mezcla. El objetivo de este trabajo fue evaluar los períodos de exposición de las semillas de Brachiaria ruziziensis al contacto prolongado con urea, en tres proporciones de mezcla con fertilizante bajo la viabilidad de la semilla y el vigor de las plántulas. En un experimento de diseño completamente al azar, se evaluó el efecto de seis tiempos (3, 6, 12, 24, 48 y 72 horas) a tres niveles de urea (50, 100 y 150 kg de N ha-1) sobre la calidad fisiológica de las semillas. Se verificó el efecto negativo del tiempo y las proporciones de fertilizantes sobre la germinación y el vigor de las semillas. El mayor efecto negativo de la exposición de las semillas a la urea, con aumentos en la inviabilidad de las semillas y disminución de las plántulas normales, ocurre en altas proporciones de fertilizante con semillas y tiempo de mezcla hasta su uso

Produção de gado de corte no Estado de Rondônia: uma proposta de sistema melhorado.

O presente trabalho apresenta uma proposta de sistema melhorado para o Estado de Rondônia, como alternativa ao sistema praticado pela maioria dos produtores dessa região.bitstream/CNPGC-2010/13217/1/COT112.pd

Sistema de produção de ovinos deslanados na Amazônia Ocidental.

Os ovinos deslanados foram introduzidos na Amazônia Ocidental pelos órgãos governamentais de extensão, pesquisa e fomento e, principalmente, pelos migrantes nordestinos. Atualmente, a região possui um rebanho superior a 100.000 cabeças, que são criadas associadas a bovinos ou não, com a finalidade de produzir carne, pele e esterco. Para o bom desenvolvimento da criação de ovinos deslanados na Amazônia Ocidental, torna-se necessário o uso de tecnologias como: padrão racial, instalações adequadas, pastejo rotativo, manejo reprodutivo e sanitário eficientes..

Programa bancos comunitários de sementes de adubos verdes em Minas Gerais.

Benefícios da adubação verde. Adubação verde e energia. O estado da arte da adubação verde em Minas Gerais. O banco comunitário. Programa Bancos Comunitários de Sementes de Adubos Verdes (PBCSAV). Da semeadura e colheita das leguminosas à semeadura do milho.bitstream/CNPAF-2009-09/28189/1/Com_165.pd