CONTRIBUTIONS DES PARTENARIATS POUR CONCEVOIR DES CONNAISSANCES AGRONOMIQUES SUR LA GESTION DE L'HERBE ET DEVELOPPER DES OUTILS ACTIONNABLES PAR DES CONSEILLERS FOURRAGERS

N° ISBN - 978-2-7380-1284-5International audienceCo-design of artifacts usable by extension services can be a long-lasting task. It partly depends on the developments of scientific knowledge. In addition, as we will show in this testimony, training and partnership with practitioners play a key role in the design of an artifact, here a tool to diagnose the opportunity of grassland management practices in a farm. Discussions between researchers and practitioners during training sessions led to the design of prototypes of articfact. Partnership between researchers and practitioners on the long term contributed to adjust the artifact, to simplify its procedure, and overall to improve its diagnosis capacity by capitalizing on researchers' and practitioners' knowledge. This experience has required adaptive capacity of researchers, leading them to adopt different research postures according to the stages in the interactions with practitioners. Researchers considered practitioners as knowledge providers by associating them to articfact co-design, or as experts to be equipped by involving them in participatory research projects

Development of Robotics Tools for Agricultural Task Achievement: The example of robot formation control

Abstract — Nowadays it is eagerly expected that, on one hand the environmental impact of agricultural activities is decreasing, and on the other hand the level of production is increasing in order to match the consumption demand of the growing worldwide population. To meet these opposite expectations, new production tools have to be developed. Recent advances in offroad mobile robotics may bring to promising solution in order to address such a problematic. Since large area coverage, as well as high flexibility, are more particularly looked for in this paper, multi-robot cooperation for field operations is investigated. The proposed framework relies on a path tracking approach dedicated to the formation control of several robots. In an off-road context, because of bad grip conditions, classical control algorithms cannot be used straightforwardly. Moreover, low level delays and stability issues (rollover risk or obstacle collision) have also to be taken into account. Adaptive and predictive control laws are here designed to achieve accurate motion control of each robot, despite highly varying and unpredictable contact conditions. The multi-robot configuration is imposed by defining set points in terms of lateral deviations and longitudinal distances between each robot. In addition, robot safety is addressed through a traversability evaluation within the vicinity of each robot. Finally, several alternative paths are constantly considered and the optimal one is decided with respect to robot stability and maximal velocity criteria, assessed from a numerical terrain model. I

Structural and electrochemical characterizations of P2 and new O3-NaxMn1-yFeyO2 phases prepared by auto-combustion synthesis for Na-ion batteries

Using auto-combustion synthesis route followed by a 1000°C heat-treatment, we succeeded to prepare four Nax(Mn,Fe)O2 phases: P2-Na0.67Mn2/3Fe1/3O2, P2-Na0.71Mn1/2Fe1/2O2, and new Na-deficient O3-Na0.82Mn1/3Fe2/3O2 and O3-Na∼0.8Mn1/2Fe1/2O2 phases. We studied their structures by X-ray Diffraction and their electrochemical properties as positive electrode in Na-cells that were reversibly charged and discharged in the 1.5 and 3.8 V range vs. Na+/Na, leading to discharge capacities between 135 and 155 mAh.g−1. The shapes of the cycling curves are discussed together with the stacking of the phases and the redox processes involved in the Na intercalation/deintercalation reaction. In some cases the Fe(IV) state is clearly reached

Une démarche participative de diagnostic d’autonomie pour une re-conception agroécologique des élevages de ruminants (DACAR)

International audienc

Methane and carbon dioxide emissions from tropical reservoirs: Significance of downstream rivers

International audienceMethane (CH4) and carbon dioxide (CO2) concentrations and water-air fluxes were measured in three tropical reservoirs and their respective rivers downstream of the dams. From reservoirs, CH4 and CO2 flux were in the range of 3 +/- 2 and 254 +/- 392 mmol.m-2.d-1, respectively. Rivers downstream of dams were significantly enriched in CH4 and CO2 originating from reservoir hypolimnions. From rivers, CH4 and CO2 flux were in the range of 60 +/- 38 and 859 +/- 400 mmol.m-2.d-1, respectively. Despite their relatively small surfaces, rivers downstream of dams accounted for a significant fraction (9-33% for CH4 and 7-25% for CO2) of the emissions across the reservoir surfaces classically taken into account for reservoirs. A significant fraction of CH4 appeared to degas at the vicinity of the dam (turbines and spillways), although it could not be quantified

Ultrafast laser-induced field emission from a single carbon nanotube based nanotip

International audienceLaser-induced electron emission from sharp tips has been observed when exploring various strong-field phenomena including multiphoton ionization (MPI) [1–3], above threshold photoionization (ATP) [4,6], and optical field emission [5]. The large optical field enhancement due to the sharp tip geometry greatly reduces the laser intensities needed to reach these strong regimes and therefore alleviates the need for high-power, low-repetition rate lasers. An additional DC field applied to the tip can be adjusted to modify the electron emission and in combination with differing laser parameters, different regimes of photoemission are attained. Investigations of the thermal response of the illumination are also studied for a variety of parameters

Réseau ECOHERBMIP : Faisabilité, performance et durabilité de systèmes de cultures économes en herbicides.

Une expérimentation "systèmes de culture " a été conduite par Arvalis-Institut du végétal en partenariat avec Terres Inovia et l'ACTA pendant 9 ans, de 2010 à 2018, dans le contexte des sols argilo-calcaires du Lauragais. Comparés à 2 systèmes "conventionnels" en rotation courte avec ou sans labour, 3 systèmes économes en herbicides dont 1 avec allongement et diversification de la rotation et mise en place de couverts végétaux en interculture, ont été évalués; Ils intègrent différents leviers agronomiques (labour, faux-semis, semis décalé, ...) et techniques de désherbage alternatives (herse étrille, binage, désherbage chimique localisé). Cette plateforme a été complétée et enrichie à partir de 2012 par 4 observatoires pilotés par les chambres départementales d’agriculture 31, 32, 81 et 82 sur lesquels 2 systèmes économes en herbicides ont été testés, en comparaison à un système témoin. Les résultats permettent de caractériser l'impact des systèmes sur l'évolution de la flore. Parmi les différents leviers mis en œuvre en vue de réduire la dépendance aux herbicides, les plus performants ont été le travail du sol (plus précisément le labour), l’allongement et la diversification de la rotation culturale, le décalage de la date de semis et le désherbage mécanique (plus particulièrement le binage et, si possible, associé à un désherbage chimique localisé sur la ligne de semis). La performance implique une combinaison de ces leviers et nécessite donc une reconception du système de culture. Une analyse multicritère des systèmes étudiés a été réalisée avec l'outil Systerre® permettant le calcul d'indicateurs économiques, techniques et environnementaux. Elle illustre entre autres une certaine fragilité économique des systèmes intégrant des cultures de diversification.An experiment of cropping systems was led by Arvalis-Institut du vegetal in partnership with Terres Inovia and ACTA for 9 years, from 2010 to 2018, in the context of the Lauragais clay-limestone soil. Compared to 2 "conventional" systems in short rotation with or without ploughing, 3 cropping systems with low herbicides input including 1 with diversification of the rotation and cover crop during intercropping period, have been evaluated; They include different agronomic practices (ploughing, fasten seedbed, shift of sowing,...) and alternative weeding technics (harrow, hoeing, localized chemical weeding). This platform was completed and enriched from 2012 by 4 observatories by the departmental agriculture chambers 31, 32, 81 and 82 on which 2 low herbicides input systems have been tested in comparison to a control system. The results allow to characterize the impact of systems on the weed evolution. Among the various levers implemented to reduce herbicide dependence, the best performers were tillage (more specifically plowing), lengthening and diversification of crop rotation, shift of sowing date and mechanical weeding (especially hoeing and, if possible, associated with chemical weed control on the sowing line). The performance involves a combination of these levers and therefore requires a redesign of the culture system. A multicriteria analysis on the studied cropping systems with the tool Systerre® was realized to calculate economical, technical and environmental indicators. It illustrates, among other things, a certain economic fragility of systems integrating diversification cultures

Diagnostiquer les pratiques fourragères en lien avec le potentiel herbager de l'exploitation. Une méthodologie adaptée au contexte AOP prairies du Massif central

National audienc