SPARTACUS : Surface, PARTicules, Ammoniac, zones Cultivées et périUrbaines

SPARTACUS : Surface, PARTicules, Ammoniac, zones Cultivées et périUrbaines. Journées scientifiques annuelles BASC 201

Modélisation de la variabilité spatio-temporelle du continuum sol-plante-atmosphère. Cas des couverts bistrates hétérogènes et épars

Annexes * INRA Bioclimatologie Grignon Diffusion du document : INRA Bioclimatologie Grignon Diplôme : Dr. Ing

Modeling the water consumption of the sparse canopy: Operational approach

International audienc

Déterminisme de la conductance stomatique dans un modèle de masse (H2O, CO2) et d'énergie

National audienc

Adaptation of a resistive model to pesticide volatilization from plants at the field scale: Comparison with a dataset

Volatilization from plants is known to greatly contribute to pesticide emission into the atmosphere. Modeling would allow estimating this contribution, but few models are actually available because of our poor understanding of processes occurring at the leaf surface, competing with volatilization, and also because available datasets for validating models are lacking. The SURFATM-Pesticides model was developed to predict pesticide volatilization from plants. It is based on the concept of resistances and takes into account two processes competing with volatilization (leaf penetration and photodegradation). Model is here presented and simulated results are compared with the experimental dataset obtained at the field scale for two fungicides applied on wheat, fenpropidin and chlorothalonil. These fungicides were chosen because they are largely used, as well as because of their differentiated vapor pressures. The model simulates the energy balance and surface temperature which are in good agreement with the experimental data, using the climatic variables as inputs. The model also satisfactorily simulates the volatilization fluxes of chlorothalonil. In fact, by integrating estimated rate coefficients of leaf penetration and photodegradation for chlorothalonil giving in the literature, the volatilization fluxes were estimated to be 24.8 ng m−2 s−1 compared to 23.6 ng m−2 s−1 measured by the aerodynamic profile method during the first hours after application. At six days, the cumulated volatilization fluxes were estimated by the model to be 19 g ha−1 compared to 17.5 g ha−1 measured by the inverse modeling approach. However, due to the lack of data to estimate processes competing with volatilization for fenpropidin, the volatilization of this compound is still not well modeled yet. Thus the model confirms that processes competing with volatilization represent an important factor affecting pesticide volatilization from plants

Synthèse des connaissances sur le transfert des pesticides vers l’atmosphère par volatilisation depuis les plantes

The agricultural activity presents the main source of the atmospheric contamination by pesticides. The occurrence of pesticides in the atmosphere concerns the research community due to their potential impacts on population and ecosystems. The volatilization from plants is higher and faster than the volatilization from soil. However, this transfer pathway is difficult to assess with few available models. The lack of knowledge on pesticide volatilization from plants is essentially linked to the complex interactions between processes occurring at the leaf surface and competing with volatilization, such as leaf penetration and photodegradation. This article presents a bibliographic synthesis of the state of knowledge on pesticide volatilization from plants, leaf penetration, photodegradation and control factors of these processes. Measuring methods and existing models describing these processes are also presented and analyzedLes niveaux de concentration des pesticides dans l’atmosphère méritent une attention particulière de la part de la recherche compte tenu de leurs impacts potentiels sur la population et les écosystèmes. L’activité agricole constitue la principale source de contamination de l’atmosphère par les pesticides. Bien que la volatilisation depuis la plante soit reconnue plus intense et plus rapide que la volatilisation depuis le sol, cette voie de transfert est à ce jour la moins bien renseignée avec peu de modèles disponibles pour sa description. Le manque de connaissances est lié essentiellement à la complexité des interactions entre les processus ayant lieu à la surface de la feuille et qui sont en compétition avec la volatilisation, notamment la pénétration foliaire et la photodégradation. Cet article présente une synthèse bibliographique sur l’état des lieux des connaissances sur le processus de volatilisation des pesticides depuis un couvert végétal, de la pénétration foliaire et de la photodégradation, ainsi que les facteurs de contrôle de ces processus. Les méthodes de mesure ainsi que les modèles existants décrivant ces processus sont également présentés et analysé

Potential for recoupling production and consumption in peri-urban territories: the case-study of the Saclay plateau near Paris, France

With growing urbanization worldwide, urban sprawl is leading to the extension of peri-urban areas inmost countries. These dynamic areas, subjected to pressure from urban planning, are contributing to the uncoupling of consumption and local agriculture. In this article we study the feasibility of recoupling production and consumption within the agri-food system of the peri-urb n area of the Saclay plateau near Paris. By using a nitrogen flow analysis based on the concept of territorial ecology, we analysed quantitative and qualitative data providing information in terms of system performances. By calculating two local efficiency indicators (one production-based indicator and one consumption-based) and a self-sufficiency capacity indicator, we assess the current and potential coupling between production and consumtion. A typology of farming systems was constructed to assess the more efficient type of farms in terms of ‘‘localisation within the agri-food system. The Saclay plateau has many assets to increase local agri-food system efficiency and to work towards ‘‘agricultural symbiosis”. However, a number of obstacles remain on both the production and the demand sides. Our study illustrates the lack of consideration of the productive function of urban and peri-urban agriculture in urban planning projects. The methods developed and the results achieved are a step towards a better integration of food issues in land planning

Echanges énergétiques et hydriques. Modélisation "1D spatialisée" appliquée à des couverts hétérogènes et épars

National audienc