Productivity and radiation use efficiency of lettuces grown in the partial shade of photovoltaic panels

Combining photovoltaic panels (PVPs) and crops on the same land unit were recently proposed as an alternative to the conversion of cropland into photovoltaic plants. This could alleviate the increasing competition for land between food and energy production. In such agrivoltaic systems, an upper layer of PVPs partially shades crops at ground level. The aim of this work was to (i) assess the effect on crop yield of two PVPs densities, resulting in two shade levels equal to 50% and 70% of the incoming radiation and (ii) identify morphological and physiological determinants of the plant response to shade. Experiments were conducted on four varieties of lettuces (two crisphead lettuces and two cutting lettuces), during two seasons. In all cases, the relative lettuce yield at harvest was equal or higher than the available relative radiation. Lettuce yield was maintained through an improved Radiation Interception Efficiency (RIE) in the shade, while Radiation Conversion Efficiency (RCE) did not change significantly. Enhanced RIE was explained by (i) an increase in the total leaf area per plant, despite a decrease in the number of leaves and (ii) a different distribution of leaf area among the pool of leaves, the maximal size of leaves increasing in the shade. Our result provides a framework for the selection of adapted varieties according to their morphological traits and physiological responses to PVP shade, in order to optimize agrivoltaic systems

Towards an agroecological viticulture: advances and challenges

To improve its sustainability, viticulture should increase the provision of ecosystem services to decrease its use of inputs and the resulting environmental impact while maintaining high socio-economic performance. Soil functions in relation with their physical, chemical and biological properties can be regulated by proper soil surface management. Cover crops deliver ecosystem services such as protection of soils, better water infiltration and nitrogen fixation. Yet to avoid trade-off between provision of services and production of grapes, the management of cover crops should adapt to climate variations and to the yield objective. Pest and diseases can be regulated by various technical levers, including the control of the grape vegetative development. The assessment of damages due to pests and disease and of their consequences on yield losses is a key component of the design of alternative strategies of crop protection. This knowledge provides clues for designing management strategies with low pesticide use and high agro-ecological performance. A French national network of experiments has quantified the reduction of pesticide use with decision support systems, biocontrol or resistant varieties. To go further the challenge is now to design agroecological vineyards that combine innovations in management, and also in spatial organization at field, farm and landscape scales

Un nouvel indicateur intégré d’évaluation des dégâts occasionnés aux grappes par des bioagresseurs majeurs au vignoble

Communication faite au cours du colloque DinABio2013, 13 et 14 novembre 2013; Tours, FranceAn original and integrative evaluation indicator has been developed to quantify the cumulated damage from major pests and diseases affecting grape bunches: downy mildew, powdery mildew, gray mould and tortricid moths. It made it possible to estimate the associated crop losses and to relate them to the plant protection strategy in different modes of production (organic farming, in-transition, conventional). Thus, overall plant losses were higher in 2012 than in 2011. The in-transition growers’ strategy, with reduced copper doses but increased numbers of sprays, led to a 20% increase in average severity on bunches (essentially due to Downy mildew). The more pragmatic approach of experienced organic growers and conventional ones (higher doses and fewer sprays) reduced the yield losses. The proposed indicator is used for two purposes, i) evaluating the quantitative losses due to pest attacksand ii) differentiating them from other non-pest ones. A more detailed analysis including the impact on performance will be achieved and published soon.Un indicateur d’évaluation, l’IEDG (Indicateur d’Evaluation des Dégâts sur Grappes), a été mis au point pour quantifier les dégâts cumulés dus aux principaux bioagresseurs affectant les grappes de raisin : mildiou, oïdium, pourriture grise et tordeuses. Il permet d’estimer la perte de récolte imputable au cortège parasitaire et de faire le lien avec la stratégie phytosanitaire adoptée (caractérisée ici par l’IFT) et le mode de production (AB, conversion, conventionnel). Ainsi, les pertes sanitaires ont été supérieures en 2012 par rapport à 2011. La stratégie phytosanitaire des viticulteurs en conversion, basée sur des réductions de dose de cuivre de près de 80% et des passages plus nombreux dans les parcelles, n’a pas été efficiente en 2012 avec des sévérités proches de 20% sur grappe, essentiellement dues au mildiou. L’utilisation de doses d’applications supérieures et moins de passages dans les parcelles limite les dommages chez les autres viticulteurs. L’indicateur proposé permet d’évaluer les pertes quantitatives générées par les attaques de bioagresseurs et de les différencier des autres pertes non parasitaires. Une analyse plus fine incluant l’effet région et l’impact sur le rendement devra être réalisée

Des légumineuses pour refonder des systèmes de grande culture plus durables adaptés au changement climatique et permettant le développement de l’agro-écologie

S’il est une cause susceptible de fédérer les énergies de la recherche et des professionnels des filièreset des territoires agricoles en France et dans le monde c’est bien celle de la re-conception de systèmes agricoles durables. Ceci suppose de penser, de conduire et d’évaluer les systèmes de culture et d’élevage et leur trajectoire dans un espace à quatre dimensions fixant des objectifs de performances économiques, environnementales et sociales ainsi que les institutions nécessaires pour appuyer ces transitions (Magrini et al., 2015). Le changement climatique est un élément incontournable qui fixe à la fois le contexte de ces dynamiques (évolution du climat et besoin d’adaptation des systèmes) et les objectifs de l’axe environnemental (réduction des gaz à effet de serre et séquestration du carbone). Dans la plupart des pays il faut en même temps accroître laquantité et la diversité des productions alimentaires tout en réduisant les intrants biophysique des systèmes de culture compte-tenu de leur empreinte environnementale sur l’eau, la biodiversité et la consommation énergétique. Dans tous les cas le travail est une variable incontournable des performances économiques et sociales ce qui a conduit dans les systèmes de grande culture à une mécanisation de toutes les opérations culturales sur laquelle il n’y aura pas de retour en arrière.Les travaux de recherche en agro-écologie et les pratiques des agriculteurs en agriculture biologique, de conservation ou intégrée convergent tous sur l’idée que cette re-conception de systèmes de culture plus durables repose sur deux piliers incontournables : la qualité du sol et la diversification des successions culturales et plus particulièrement par les légumineuses. Force est de constater cependant qu’en dépit des qualités indéniables de ces cultures (Schneider et Huyghe, 2015) leur contribution aux assolements de grande culture reste depuis 30 ans cantonnée dans la plupart des systèmes à quelques % de la surface cultivée en céréales. Et si nous faisions fausse route dans la façon de considérer ces « merveilleuses légumineuses » et leur contribution à des systèmes de culture plus durables ? Pour ouvrir le débat nous proposons de changer de point de vue en repensant l’innovation et l’accompagnement institutionnel des légumineuses autour de 5 principes que nousillustrerons sur l’exemple du pois chiche et de la luzerne en France. 1. Remettre la symbiose à sa place. Les légumineuses sont uniques dans les espèces cultivées, grâce à leur capacité à fixer l’azote de l’air par la symbiose avec des bactéries (rhizobium), ce qui leur permet de ne pas être en situation de carence en azote une fois les réserves de la graine et l’azote minéral du sol consommés (Voisin et Gastal, 2015). Ceci implique que la contribution majeure de cette symbiose à la réduction des engrais azotés dans les systèmes de culture est d’introduire dans les successions une culture qui peut accumuler autant d’azote que des céréales sans aucun apport d’engrais azoté. Une légumineuse introduite dans une rotation colza-blé-orge peut ainsi permettrede réduire d’un quart l’utilisation moyenne annuelle d’engrais en maintenant le même rendement sur ces 3 cultures. La légumineuse peut aussi apporter une deuxième fois de l’azote à la culture qui la suit mais cela ne leur est pas spécifique car on le doit principalement à l’azote résiduel des pailles et des racines. Par ailleurs les effets assez systématiquement positifs des légumineuses sur le rendement des céréales suivantes sont tout autant attribuables à la rupture des cycles des bioagresseurs et des adventices qu’à cette fourniture d’azote (Jeuffroy et al., 2015)

Introduction to the Farming Systems Design Special Issue

International audienc

Converting to organic viticulture increases cropping system structure and management complexity

Organic viticulture is an effective cultivation method that can reduce the environmental impacts of grape growing while maintaining profitability. For some vineyards, simple adjustments can suffice to make the conversion to organic farming; however, for most, major changes in system structure and management must be implemented. Here, we showed for the first time that converting to organic viticulture impacts vineyard complexity. We used six complexity indicators to assess modifications to cropping system structure and management : number of fields, number of difficult-to-manage fields, vineyard area, number of field interventions, number of technical management sequences, and number of management indicators. These six indicators were assessed through interviews carried out with winegrowers from 16 vineyards between 2008 and 2012. Changes in vineyard performances during conversion were also measured. We demonstrate that conversion to organic viticulture increased the complexity of vineyard structure and management for the 16 vineyards surveyed. While this increase allowed agronomic performances in all vineyards to be maintained, it also came with an increase in labor requirements (of up to 56%) compared to conventional agriculture. We conclude that the six indicators are appropriate for assessing changes in vineyard complexity and could be extended to all agricultural systems to better anticipate the implications of organic farming conversion for a farm’s biophysical technical, and decisional sub systems

Converting to organic viticulture increases cropping system structure and management complexity

Organic viticulture is an effective cultivation method that can reduce the environmental impacts of grape growing while maintaining profitability. For some vineyards, simple adjustments can suffice to make the conversion to organic farming; however, for most, major changes in system structure and management must be implemented. Here, we showed for the first time that converting to organic viticulture impacts vineyard complexity. We used six complexity indicators to assess modifications to cropping system structure and management : number of fields, number of difficult-to-manage fields, vineyard area, number of field interventions, number of technical management sequences, and number of management indicators. These six indicators were assessed through interviews carried out with winegrowers from 16 vineyards between 2008 and 2012. Changes in vineyard performances during conversion were also measured. We demonstrate that conversion to organic viticulture increased the complexity of vineyard structure and management for the 16 vineyards surveyed. While this increase allowed agronomic performances in all vineyards to be maintained, it also came with an increase in labor requirements (of up to 56%) compared to conventional agriculture. We conclude that the six indicators are appropriate for assessing changes in vineyard complexity and could be extended to all agricultural systems to better anticipate the implications of organic farming conversion for a farm’s biophysical technical, and decisional sub systems

Cropping the Diversity » for improved sustainability of Agricultural Systems

Présentation de l’initiative CropDiv "Cropping the Diversity" for improved sustainability of Agrilcultural Systems, une communauté de pratiques à vocation internationale

A typical application of SEAMLESS-IF at meso level: the nitrate directive and the conservation agriculture scenarios in Midi-Pyrenees

International audienceThis deliverable describes a typical meso-level application of SEAMLESS-IF. This application serves two main purposes within the SEAMLESS project. First of all it served as Test Case 2 (TC2) to test the various prototypes delivered by the SEAMLESS project and guide the development of the framework by identifying the requirements for a real-world application of the framework for ex-ante policy and technological innovations analysis. The second purpose of this application and main focus of this deliverable is to illustrate the potential use of SEAMLESS-IF to adress meso-level environmental questions across domains and scales. This deliverable builds on deliverables prepared throughout the SEAMLESS project, compiling and updating the essence of each of these individual deliverables to a final application with SEAMLESS-IF. The deliverable highlights the potential of SEAMLESS-IF to analyse meso-level incitation for better water and nitrogen managements. For this purpose three scenarios have been defined, combing different water and nitrogen managements such as suggest to improve nitrogen management for cereal crop based on simplify N balance. The objective of this scenario is to calculate new amounts of irrigation based on plant available water (PAW) which will be daily estimated by using the APES model. The last scenario is a combination of the previous two scenarios. The CAP2003 applied with 2013 conditions, by including exogenous driving forces, is taken as a reference. After a brief description of the Nitrate Directive and Water Framework Directive and their main measures in order to reduce nitrogen leaching and water consumption, a detailed description of the three modelling phases of SEAMLESS-IF is given. For each part, the main elements and data needed for each scenarios is described

Trade-offsbetween production and tree biodiversity in coffee agroforests of Guinea andtheir contribution to landscape resilience and farmers livelihood

Coffeeagroforests are typical of the multi-strata cropping systems for which there isa growing interest as a pathway towards sustainable agriculture. Due to theirpluri-specificity, they provide interesting trade-offs between services andproductions that participate to resilience of tropical landscapes and offarmers livelihoods. There is however still little knowledge about thetrade-offs between coffee yield (one of the components of production) and treebiodiversity (one of the component of ecosystems services) on the basis offield observations. Our study aims to assess these trade-offs on coffeeagroforest plots in the region of Guinée Forestière (Guinea). We sampled 27coffee agroforest plots clustered into three shade levels over the coffeestand. On each plot, we characterized (i) canopy structure, (ii) treebiodiversity (iii) coffee yield and (iv) farmers’ practices. Data were alsocollected on forest stands as well as monocrop coffee stands to be used asreference of tree biodiversity and coffee production respectively. Coffee plantdensity was around 1030 (±330) ha-1 without significant difference between theshade levels groups. Tree biodiversity of mature trees and tree seedling wassignificantly higher in forest than in agroforest plots. Within agroforestplots, diversity of mature trees was higher in high shade plots than in lowshaded plots, whereas tree seedling diversity was similar among the shadelevels. Coffee yield decreased when shade cover increased on coffee stands (r²:0.36), with significant differences of yield per coffee plant and per habetween the high shade (129 ± 161 kg. ha-1.year-1) and low shade plots (1002 ±735 kg. ha-1.year-1). The level of intensification of farmers’ practices wasnot correlated with coffee yield and tree biodiversity. Despite a highvariability within a shade level group, coffee yield and mature treebiodiversity were significantly correlated and their relationship followed aconcave form. Using natural forest as a reference for tree biodiversity andmonocrop coffee fields as a reference for yield, discuss the tradeoffs betweeneconomic return from production and biodiversity conservation and how croppingsystem structure and management could help to shift the relationships towards aconvex curve. Among medium shade coffee agroforest plots, some fields suggest asignificant leeway to design agroforest structure and to manage their input inorder to combine, in a profitable way, the production of coffee berry andecosystems services mediated through tree diversity. Including the productsfrom other plants during the lifetime of the agroforest provides additionalleeway in the search for the best trade-offs between farmers’ livelihoods andlandscape resilience