315 research outputs found
Registros e análises de informações para o gerenciamento eficiente de empresas rurais.
A importância das informações para o processo decisório; Ferramentas gerenciais desenvolvidas pela pesquisa; Considerações finais.bitstream/item/59149/1/Documentos-220.pd
Avaliação econômico-financeira de sistemas de produção orgânica de 'Niágara Rosada'.
Dado que o desenvolvimento de sistemas de produção orgânica, em relação aos convencionais, implica em mudanças importantes na estrutura e na tecnologia empregadas, buscou-se mensurar e analisar, em condições determinísticas e de riscos, os níveis de eficiência econômica e de viabilidade financeira da produção orgânica de 'Niágara Rosada', sem e com o uso de cobertura plástica, desenvolvida pela Embrapa Uva e Vinho.bitstream/item/124077/1/Circular-Tecnica-101.pd
Quantitative analysis of headspace volatile compounds using comprehensive two-dimensional gas chromatography and their contribution to the aroma of Chardonnay wine.
The quantitative determination of volatile compounds of Chardonnay wines using HS-SPME-GC × GC/TOFMS along with the determination of odor activity value (OAV) and relative odor contribution (ROC) of volatiles are reported for the first time. The use of GC × GC/TOFMS for the analysis of Chardonnay wine of Serra Gaucha resulted in the tentative identification of 243 compounds, showing the superior performance of this analytical technique for this specific varietal wine, considering that the number of compounds usually separated by 1D-GC for this type of wine is lower. Furthermore, 42 compounds co-eluted in the first dimension and 34 of them were separated in the second dimension, while the others were resolved by spectral deconvolution (8), which indicates that the conventional 1D-GC/MS may result in misleading results. The calculation of OAV and ROC allowed the determination of the volatile compounds that presented the greater contribution to wine aroma. Ethyl octanoate, ethyl hexanoate, ethyl butanoate, and beta-damascenone showed the highest OAV and ROC values, although other 43 compounds showed also potential to contribute to wine aroma. Figures of merit of the developed method were: accuracies from 92.4 to 102.6%, repeatability from 1.2% to 13.4%, LOD from 0.001 ?g L?1 (ethyl isovalerate and hexanoic acid) to 2.554 ?g L?1 (ethyl 3-hydroxybutanoate), LOQ from 0.003 ?g L?1 (ethyl isovalerate and hexanoic acid) to 7.582 ?g L?1 (ethyl 3-hydroxybutanoate)
Bilan du phosphore dans un bassin versant du lac Léman : Conséquences pour la détermination de l'origine des flux exportés
Cet article s'intéresse à la dynamique du transfert du phosphore dans un bassin rural de la région lémanique, le bassin versant du Foron (51,5 km2). Nous montrons qu'en établissant, pour les périodes de tarissement, la relation concentration moyenne en phosphore - débit moyen à l'exutoire, il est possible d'évaluer globalement:1) la rétention du P dans le réseau hydrographique lors de ces périodes; 2) la contribution moyenne des sources ponctuelles de P aux exportations du bassin.La rétention est un phénomène temporaire, mais c'est une étape clé de la dynamique du phosphore. Elle crée d'importants stocks de P dans le réseau hydrographique; ces stocks se situent pour l'essentiel au niveau des sédiments comme l'ont montré diverses études antérieures et sont exportés lors des crues. Les quantités stockées à l'issue de longs étiages dépassent souvent largement les exportations enregistrées pendant les plus fortes crues. La rétention s'accompagne d'une transformation partiellement irréversible de la spéciation du phosphore transféré.Ces phénomènes sont pris en compte pour établir des bilans annuels de pollution, et notamment la balance diffus - ponctuel.The effective management of phosphorus in watersheds requires knowledge of the origin and magnitude of phosphorus inputs. However, for large and complex watersheds, it is impossible to determine the phosphorus mass balances by measuring the flow from each source and the rate of transfer of phosphorus originating from upstream. Because of these difficulties, we have developed a strategy based on the measurement of phosphorus mass balances during base flow periods (with no storm-flow, which means with a constant or decreasing flow). This approach was applied to the Foron River watershed (drainage area 51.5 km2, annual average water discharge 0.5 m3 /s).The Foron River, a hillside stream with a torrential flow regime, is a tributary of Lac Léman (a large meso-eutrophic lake also known as Lake Geneva). Land use within the Foron watershed is diverse, with 50% of the watershed area being in a naturally forested area (on steep upland slopes), 36% in agricultural land lying on a gentle relief of moraine deposits (70% permanent pasture and hay meadows, 30% cereal grain crops) and 3% in marshes. The population is scattered amongst four small villages, with an overall density of about 100 inhabitants per km2. Stream flow in the river was continuously monitored and automatically sampled at the outlet from 1990 to 1993. Additional grab samples were taken at various locations, springs, agricultural sub-watersheds and brooks in the naturally forested area. Total suspended solids, soluble total phosphorus, orthophosphate and total phosphorus were determined according to standard methods. In addition, sampling was carried out to determine phosphorus stored in river sediments in places that are known to be temporary sinks for sediments.To validate the efficiency of the approach, we carried out a detailed study of the point sources and the sewage systems in the watershed. Only two-thirds of domestic wastewaters were processed in treatment plants. The minimum load of point source inputs was established to be about 60 kg total P per week and many point sources (that is to say discharged at discrete locations) remained unidentified (i.e., not all households were connected to sewers, farmsteads contributed for unknown quantities of total P).During base flow periods, phosphorus was predominantly soluble and orthophosphate was found throughout the hydrographic network. Particulate phosphorus and suspended matter concentrations were negligible (respectively 0.8 m3 /s, a constant P export regime was reached as all the inputs were transported to the outlet. Consequently, output at the outlet was equal to input into the river. This approach permits the calculation of the total point sources. Knowing the inputs from point sources and the total P export at the outlet, we can calculate the diffuse sources.Significant relationships between weekly mean total-P, soluble-P or orthophosphate concentrations at the outlet and weekly mean discharge were established to validate these observations. The best fit of these measured values didn't follow a standard law of dilution because the dilution effect was attenuated by the antagonist effect due to the increase in P transport inputs from sewage with increasing discharge. ([soluble P]=0.02+ 0.148 Q-1/2 ; n=82; r2 =0.8).During base flow when Q < 0.8 m3 /s, a portion of phosphorus inputs accumulated in the river biota and sediments through deposition, biological uptake and sorption. This accumulation may explain the higher levels of total-P and the easily exchangeable P in the sediments downstream of point source discharges. The efficiency of these storage processes depends not only on water discharge, but also (secondarily) on some characteristics of the antecedent hydrological conditions. We found that the amount stored increased significantly in the weeks following large storm-flows. We assumed that this indicated the effect of an intense exchange of the P loaded sediments with unsaturated sediments that were generated by erosion of natural upstream areas. As in-stream processes alter phosphorus speciation, a part of soluble-P becomes particulate. During storm-flows following base flow periods with a discharge lower than the limit discharge, the stored phosphorus was released from both particulate and soluble forms and exported. We calculated an annual mass balance of soluble phosphorus to evaluate the amount of particulate phosphorus exported at the outlet due to the transformation of phosphorus from soluble to particulate forms. The result obtained suggested that ¼ of particulate-P (1 t per year) resulted from this speciation change.To summarize, analyses of phosphorus mass balances during base flow could lead to a new procedure to evaluate the mean total mass of P originating from point sources, without referring to field surveys. In addition, this procedure allowed the quantification of both total-P storage as well as changes in speciation that occur during transfer of phosphorus in the hydrographic network
Determination of the possible contribution to aroma using odor activity values of volatile compounds of wines analyzed by comprehensive two dimensional gas chromatography.
The aim of this study was to use the HS-SPME-GC × GC/TOFMS to quantify volatile compounds of wines produced with Chardonnay grapes in Serra Gaúcha region, Brazil and determine their possible contribution to aroma through the determination of OAV for each tentatively identified compound
Volatilidade dos retornos econômicos associados à integração lavoura-pecuária no Estado do Paraná.
O setor agropecuário brasileiro há grande diversidade e heterogeneidade de sistemas de produção, que tendem a ser cercados por amplo número de fatores de riscos. Embora não possam ser completamente eliminados, os riscos podem ser minimizados mediante adoção de algumas estratégias, como a diversificação com atividades agrícolas e pecuárias. Assim, partindo de resultados históricos de pesquisas para a agropecuária do estado do Paraná e utilizando, como medida principal. o value-at -risk (ou valor em risco), analisou-se a volatilidade do retornos econômicos de sistemas com integração lavoura-bovinocultura de corte, diante de sistemas especializados na produção de grãos ou na bovinocultura de corte. As análises apontaram que. no curto prazo. a integração tende a gerar melhores resultado' econômicos que os demais sistemas analisados
Viabilidade financeira e riscos associados à integração lavoura-pecuária no Estado do Paraná.
No setor agropecuário brasileiro, existe grande diversidade e heterogeneidade de sistemas de produção, que tendem a ser cercados por amplo número de fatores de riscos. Embora os riscos não possam ser completamente eliminados, eles podem ser minimizados mediante a adoção de algumas estratégias, como a diversificação com atividades agrícolas e pecuárias. Assim, buscou-se analisar, de forma comparativa e sob situações de riscos operacionais e de mercado, a viabilidade financeira de sistemas com integração lavoura-bovinocultura de corte frente a sistemas caracterizados pela exploração de grãos ou pela especialização na bovinocultura de corte. Em termos metodológicos, utilizando dados da agropecuária do Estado do Paraná, especialmente da microrregião de Guarapuava, foram obtidos indicadores financeiros de longo prazo: valor presente líquido, taxa interna de retorno e razão benefício/custo. Com base nos resultados, conclui-se que, tanto em situações determinísticas como de incertezas, o sistema de integração é a alternativa que propicia os melhores resultados financeiros
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