L’enherbement du vignoble alsacien : un bilan positif vis-à-vis du transfert de nitrates

La pratique culturale consistant à associer deux cultures au cycle végétatif déphasé : la vigne (Vitis Vinifera) et l’herbe (graminées, fétuques) est évaluée. Le suivi sur deux saisons de deux parcelles (l’une enherbée un rang sur deux, l’autre désherbée) montre l’influence de l’herbe sur la dynamique du cycle de l’eau et des nitrates. Sur les deux campagnes de mesure (1998/1999 et 1999/2000), on constate une perte hydrique supplémentaire de 70 mm/an par évapotranspiration sur parcelle enherbée un rang sur deux. La présence d’herbe tamponne la fertilisation, mobilise l’azote sous forme organique et non plus minérale et provoque une réduction des flux d’azote jusqu’à un facteur 7.Cultivation method consisting in associating two row cultures with a vegetative cycle out of phase: the vineyard and the grass is evaluated. The two years follow-up of two plots (one with grass each other row, the other weeded) shows the impact of the grass on the dynamics of the water and nitrate cycle. During the two series of measurement (1998/1999 and 1999/2000), we note an additional loss of 70 mm/an per evapotranspiration on the plot with grass. The presence of grass also regularizes any fertilization and mobilizes the nitrogen in a organic form and either mineral form. The presence of grass on a plot causes a reduction of nitrogen flows until a factor 7.Es wird die Anbaupraxis bewertet, die zwei kulturen mit phasenlosem Vegetationszyklus verbindet : die Weinrebe (Vitis Vinifera) und das Gras (Gramineen, Festuken). Die jährlich zweimalige Fruchtfolge auf zwei Parzellen, die eine mit, die andere ohne Gras, zeigt den Einfluß des Grases auf die Dynamik des Wasserzyklus und der Nitrate. Es wird ein zusätzlicher hydrischer Verlust von 70 mm/Jahr durch Evatranspiration auf begraster Parzelle festgestellt. Die Mitwirkung von Gras puffert die Fruchtbarmachung, mobilisiert den Stickstoff in organischer und nicht mehr mineralischer Form und ruft eine Reduktion des Stickstoffflusses bis zum Faktor 7 hervor

Pesticide contamination interception strategy and removal efficiency in forest buffer and artificial wetland in a tile-drained agricultural watershed

Yves couqet : present adress : UMR7327 on sept. 2012International audiencePesticide pollution is a major threat to aquatic ecosystems that can be mitigated through complementary actions including buffer zones (BZs). This paper discusses the results of 3 yr of field-scale monitoring of the concentration and load transfer of 16 pesticides out of a tile-drained catchment (Bray, France) and their reduction through two BZ: an artificial wetland (AW) and a forest buffer (FB). Typically, the highest concentrations were measured in the first flows following pesticide applications or resuming after periods of low or no flow. An open/close water management strategy was implemented to operate the parallel BZ based on pesticide applications by the farmer. The strategy was efficient in intercepting molecules whose highest concentrations occurred during the first flows following application. Inlet vs. outlet pesticide load reductions ranged from 45% to 96% (AW) and from −32% to 100% (FB) depending on the pesticide molecule and the hydrological year. Partly reversible adsorption was a dominant process explaining pesticide removal; whereas, degradation occurred for sufficiently long water retention time. Apart from the least sorbing molecules (e.g., isoproturon), BZ can partially remove pesticide pollution

Modelling of a constructed wetland for pesticide mitigation

10 p.International audienceThe Water Framework Directive and the Ecophyto 2018 plan provides for measures against water chemical pollution. In the agricultural context, pesticide are a real stress for surrounding environment. Measures have been taken to reduce this stress, namely the reduction of chemical application, and the implantation of buffer zones like artificial wetland at the outlet of the agricultural watershed. A PhD thesis has begun in November 2012 on the modelling of the wetland functioning for pesticide mitigation. This work takes place in the team TAPAHS in the unit Hydrosystem and Bioprocesses of the Institute Irstea. The motivation of this work takes birth in the preceding studies of the team on the removal efficiency of a wetland regarding several pesticides. Several tools are yet available to reach our objectives. An experimental site has been instrumented in the city of Rampillon (France) and a state of art is under construction. The bibliography's study focus on two subjects: the tracer experiments and the constructed wetlands models which have been developed. These tools lead to a methodology which we propose to follow for the next steps of the PhD thesis

Land drainage functioning and hydrological impacts in rural catchments: model development and field experiments

International audienceThe development of an integrated theory of subsurface drainage based on hydrology and hydrogeology concepts is presented. The historical context, the main hypothesis derived from the Boussinesq equation and the validation of the model predictions are discussed. Theoretical developments of this equation demonstrate that a single parameter (σ)-a combination of soil and drainage system properties-is sufficient for predicting the dynamics of subsurface drain flow rates. We also demonstrate that these drain flow rates are a function of the level of water replenishment in the system (classically the water table elevation), of the recharge intensity of the aquifer and of a buffer function related to the swelling or deflation of the water table shape during recharge events. For values of σ > 1, the buffer role of the water table is negligible. In that case approx. 13% of the water table recharge contributes to the flow rate, which is shown to explain the observed disconnection between water table elevations and peak flow rates at the outlet of classic agricultural drainage systems and to predict these peak flow rates accurately. A modelling approach based on this theory and validated experimentally (SIDRA model) allowed us to test the quality of the peak flow prediction. The SIDRA model also includes a surface runoff module and has been coupled to different modelling tools and used to analyse the impacts of subsurface drainage on water quality. The approach contributed towards the development of tools that helped to connect better the drainage systems to the hydrological functioning of watersheds

High denitrification potential but low nitrous oxide emission in a constructed wetland treating nitrate-polluted agricultural run-off

Acknowledgements The study was conducted within the framework of several scientific projects: “Efficacité des Zones Tampons” by OFB (French Office for Biodiversity, and technical group “Zones Tampons “), and HydroGES (financed by the Agency for the Environment and Mastery of Energy, ADEME). The travel was supported by two French–Estonian Parrot RTD projects “Ecological engineering for nutrient control in rural catchments” and “Process-based approach and enhanced technologies of treatment wetlands” (2014–2016). The PIREN-Seine programme and the Fédération Ile-de-France de Recherche pour l'Environnement (FIRE) are also acknowledged for their support. The authors also thank AQUI'Brie association for their support and stakeholders' involvement. This study was also supported by the Estonian Research Council (grants IUT2 16, PRG352 and MOBERC20) and by the EU through the European Regional Development Fund (Centres of Excellence ENVIRON and EcolChange, and MOBTP101 returning researcher grant by the Mobilitas Pluss programme).Peer reviewedPostprin

Réduire les fuites de nitrate au moyen de cultures intermédiaires : conséquences sur les bilans d'eau et d'azote, autres services écosystémiques

La présence de nitrate en excès dans les eaux de surface et les nappes phréatiques pose des problèmes de santé publique et de dégradation de l’environnement. C’est d’abord un enjeu de santé publique notamment pour les nappes phréatiques, avec la nécessité de distribuer une eau de boisson présentant une teneur inférieure à la norme de potabilité qui est de 50 mg de nitrate par litre. C’est aussi un enjeu de protection de l’environnement pour les eaux de surface, en particulier pour certains bassins versants proches de la mer, comme en Bretagne ; le transfert rapide du nitrate des zones agricoles vers la mer induit une eutrophisation des zones côtières

The Role of Ponds in Pesticide Dissipation at the Agricultural Catchment Scale: A Critical Review

Ponds in agricultural areas are ubiquitous water retention systems acting as reactive biogeochemical hotspots controlling pesticide dissipation and transfer at the catchment scale. Several issues need to be addressed in order to understand, follow-up and predict the role of ponds in limiting pesticide transfer at the catchment scale. In this review, we present a critical overview of functional processes underpinning pesticide dissipation in ponds. We highlight the need to distinguish degradative and non-degradative processes and to understand the role of the sediment-water interface in pesticide dissipation. Yet it is not well-established how pesticide dissipation in ponds governs the pesticide transfer at the catchment scale under varying hydro-climatic conditions and agricultural operation practices. To illustrate the multi-scale and dynamic aspects of this issue, we sketch a modelling framework integrating the role of ponds at the catchment scale. Such an integrated framework can improve the spatial prediction of pesticide transfer and risk assessment across the catchment-ponds-river continuum to facilitate management rules and operations

Réduire les fuites de nitrate au moyen de cultures intermédiaires : conséquences sur les bilans d'eau et d'azote, autres services écosystémiques : Synthèse du rapport d'étude

Synthèse du rapport d'étude. Le présent document constitue la synthèse de l’étude sollicitée conjointement par le Ministère de l'Ecologie, du Développement Durable et de l'Energie et le Ministère de l’Agriculture et de l’Agroalimentaire et subventionnée par le Ministère de l'Ecologie, du Développement Durable et de l'Energie (étude n° 2100450303). Son contenu n'engage que la responsabilité de ses auteurs. Le rapport d’étude, source de cette synthèse, a été élaboré par les experts scientifiques sans condition d’approbation préalable par les commanditaires ou l’INRA. La synthèse a été validée par les auteurs du rapport

Réduire les fuites de nitrate au moyen de cultures intermédiaires : conséquences sur les bilans d'eau et d'azote, autres services écosystémiques : Synthèse du rapport d'étude

Synthèse du rapport d'étude. Le présent document constitue la synthèse de l’étude sollicitée conjointement par le Ministère de l'Ecologie, du Développement Durable et de l'Energie et le Ministère de l’Agriculture et de l’Agroalimentaire et subventionnée par le Ministère de l'Ecologie, du Développement Durable et de l'Energie (étude n° 2100450303). Son contenu n'engage que la responsabilité de ses auteurs. Le rapport d’étude, source de cette synthèse, a été élaboré par les experts scientifiques sans condition d’approbation préalable par les commanditaires ou l’INRA. La synthèse a été validée par les auteurs du rapport