Relações entre agricultura orgânica e agroecologia: desafios atuais em torno dos princípios da agroecologia.

Resumo: Neste artigo, exploramos a relação entre Agroecologia e Agricultura Orgânica. O debate na comunidade científica em alguns países e a análise das posições ou discursos de pesquisadores e artigos apontam para distintas combinações, trocas e interações entre a Agricultura Orgânica e Agroecologia. Nesse sentido, primeiramente, com base na revisão de literatura, mostramos distintas interações entre esses estilos de agricultura. Além disto, analisamos as controvérsias das agriculturas em foco, bem como apresentamos uma síntese de dois estudos de caso para ilustrar a aplicação prática de princípios da agroecologia, avaliando práticas e valores éticos, relacionando-as com as lógicas familiares ou patronais de funcionamento da produção. Concluímos que as relações entre os estilos de agricultura não podem ser reduzidas a uma simples oposição entre um campo científico e um domínio prático. Diversos elementos devem ser tomados em conta, entre os quais o grau de integração sociocultural (valores) à sociedade, as práticas e a inserção no mercado. Estudos no território brasileiro exemplificam a diversidade de relações existentes, seja inclusiva ou exclusiva, observando-se uma fluidez entre conceitos de agroecologia e agricultura orgânica

Geochemistry of clay dunes and associated pan in the Senegal Delta, Mauritania

Since the construction of the anti-salting Diama dam, a resumption of aeolian deflation has been observed in the Senegal delta and particularly in Diawling National Park. It results in the formation of many clay dunes with high salt concentrations. The soft powdery structure observed on the soil surface, affected by aeolian deflation is due to rapid salt crystallization. In order to identify the mineralogy of the salt involved in this environment, the chemistry of soil and groundwater was studied along a transect from a pan to the associated clay dune. Equilibria computation and field and scanning electron microscope (SEM) observations indicated that the changes observed in the chemical facies of the solution were due to the following precipitation sequence : calcite to gypsum to halite. A progressive but significant fixing of Na+ onto the clay particles was observed. The calcite deposition in the soil was limited by exhibition of the potential acidity arising from the former mangrove site soils. It resulted in high equilibrating pCO2. This study intended to test a new extension to the Debye-Hückel law for concentrated chlorurated sodic waters. The relationship between chloride amounts and the residual alkalinity concept confirmed that calcite and gypsum formation and the exchanges between Na and Ca are the main phenomena responsible for the changes observed in the soil solution (r2 = 0.99). (Résumé d'auteur

Mechanisms affecting stormflow generation and solute behaviour in a Sahelian headwater catchment

The aim of this study was to analyse stormflow processes and the behaviour of solutes therein (Ca2+, Mg2+, Na+, K+, alkalinity, NO3-, So(4)(2-), Cl-, Si), during flood events in tropical semi-arid conditions. The study site was a small Sahelian catchment (1.4 ha) located in northern Burkina Faso. Runoff and rain water was sampled over a 2-year period (1999 and 2000). In addition to dissolved load, suspended load was measured in the stream water collected at the outlet of the catchment. Isotopic tracing using 6180 was also conducted during two very different flood events. The results indicated that: (i) event water was by far the major contributor to the stream stormflow, with Hortonian overland flow being the. main stormflow process at work; (ii) a small fraction of pre-event soil water may have contributed during the recession of heavy flood with wet antecedent conditions; (iii) solute concentrations were higher in runoff compared to rainwater. With the exception of NO3- and Cl-, the highest concentrations were measured at the onset of floods, and almost always decreased during the rising stage of the hydrographs; (iv) a good correlation was found between suspended load and the concentrations of Ca2+, Mg2+, alkalinity and Si. It was concluded that fast physico-chemical interactions between event water and reactive suspended phases may explain most of the chemical changes between rainwater and floodwater

Controvérsias e relações entre agricultura orgânica e agroecologia.

Resumo: Apesar de o modelo agrícola convencional ou industrial ter proporcionado aumentos significativos de produtividade dos cultivos e formado sistemas "aparentemente" rentáveis, tem sido severamente questionado por estar associado a uma série de problemas ecológicos e socioambientais. As agriculturas tidas como alternativas ao modelo convencional são consideradas com potencial para contribuir e enfrentar esses problemas. Entre elas estão aquelas relacionados à segurança alimentar e à preservação do meio am biente, tais como a Agroecologia (AE) e Agricultura Orgânica (AO). Para além de objetivos comuns, ambas (AE) e (AO) se referem à ecologia e questionam o modelo tecnológico implantado durante o século XX

Opening Up Access to Scientific Information: Recommendations for Improving Virtual Repositories and Online Communities

Opening up the access to scientific information is an increasing demand and crucial need for researchers and also for all citizens, communities and societies: VOA3R, the European initiative for the Virtual Open Access Agriculture & Aquaculture Repository, has established the online platform connecting digital libraries and facilitating virtual communities with unique opportunities for sharing scientific and scholarly research related to agriculture, food, and environment. This publication presents the main outcomes and recommendations of VOA3R, the European initiative for the Virtual Open Access Agriculture & Aquaculture Repository. This flagship project supported by the European Commission facilitated, improved and sustained the open access to all European and international digital contents, scientific information and research results as well as their online discussion and exchange. The main recommendations derived and drawn from the selected five key tasks and activities (quality management, elicitation of the user requirements, social networking services, content population, and evaluation by experiments and trials) were presented in brief: They were also identified by the evaluation of the experiments and trials and and their relation between the two dimensions required efforts (indicated by the realization type from easy to difficult) and expected effects (indicated by the impact from short- to long-term) were indicated in a first overview. That allows also other and future initiative to benefit from the achieved VOA3R results and insights. VOA3R has achieved successfully its objectives and went beyond them, also analysed and evaluated through the experiments and trials: VOA3R could establish the online platform connecting digital libraries and facilitate services and social networking including virtual communities. Thus, it can be summarized that VOA3R provided and continuously provides through the sustainability strategy unique opportunities for sharing scientific and scholarly research related to agriculture, food, and environment. For open access to the best scientific information in Europe and worldwide

Handbook Twitter for Research, 2015 / 2016

International audienceThis handbook published by EMLYON Press gathers recent studies where data collected from Twitter helped explore fascinating questions in linguistics, marketing, urban studies and beyond.It comprises 13 chapters written by an international group of academics who participated in the conference "Twitter for Research" organized by EMLYON Business School in Lyon, France in April 2015. The contributing author