• Energy Research

Trois démarches de conception de systèmes de culture ont été comparées sur leur contribution à la gestion durable des adventices : (i) conception par expertise d’acteurs multiples ; co-conception par des agriculteurs (ii) d’un système innovant lors d’ateliers ponctuel ou (iii) de systèmes innovants pour chaque agriculteur d’un groupe sur une démarche de long terme. Les systèmes définis ont été simulés avec le modèle de dynamique de la flore adventice FLORSYS. Une Analyse en Composantes Principales des résultats de six indicateurs décrivant la nuisibilité des adventices pour la production, la diversité des adventices et l’intensité d’usage d’herbicides a été réalisée. Tout d’abord, la nuisibilité des adventices et l’usage d’herbicides ne sont pas corrélés. Ensuite, les systèmes innovants conçus selon la méthode (i) conduisent à des changements plus importants et contrastés, à l’inverse de la co-conception par des agriculteurs, particulièrement avec des systèmes conçus pour chaque agriculteur. Enfin, l’évolution de la durabilité a été évaluée avec le modèle d’évaluation multicritère DEXiPM. La durabilité évolue plus fréquemment, de manière positive pour les méthodes de conception (i) et (ii). Néanmoins, les seuls systèmes innovants combinant réduction significative de la nuisibilité des adventices pour la production et augmentation de la durabilité sont issus du groupe (iii), avec des modifications profondes de la rotation (réduction du blé tendre, abandon de la betterave) envisagées après 10 ans de conception pas-à-pas. Ces résultats illustrent les différences et complémentarités de ces différentes méthodes.Abstract : Comparing methods for designing innovative cropping systems aiming at sustainable weed managementThree methods of innovative design for cropping systems were compared for their contribution to sustainable weed management: (i) de novo expert design by multiple stakeholders; co-design by farmers (ii) of one cropping system during workshops; (iii) of cropping systems for each farmer member of a DEPHY network group over several years. The weed simulation model FLORSYS was used to evaluate these systems with six indicators, describing weed harmfulness for crop production, weed contribution to biodiversity and herbicide use. A principal component analysis on this dataset illustrated that there is no correlation between herbicide use and weed harmfulness for crop production. De novo expert design led to bigger changes in practices and systems performances, compared to co-design with farmers, especiallyCavan N., et al.190 Innovations Agronomiques 81 (2020), 189-200when innovative systems are designed for each farmer of a group. The evolution of sustainability of these cropping systems was assessed with the multicriteria assessment model DEXiPM and again more changes, often positive, were found with the design methods (i) and (ii). However, only a few innovative cropping systems designed with method (iii) were able to reduce weed harmfulness for production while enhancing sustainability, thanks to major changes planned in crop sequences (winter wheat reduction and sugarbeet removal), after ten years of step-by-step design. These results illustrate differences and complementarities of these design methods. Three methods of innovative design for cropping systems were compared for their contribution tosustainable weed management: (i) de novo expert design by multiple stakeholders; co-design by farmers(ii) of one cropping system during workshops; (iii) of cropping systems for each farmer member of aDEPHY network group over several years. The weed simulation model FLORSYS was used to evaluatethese systems with six indicators, describing weed harmfulness for crop production, weed contribution tobiodiversity and herbicide use. A principal component analysis on this dataset illustrated that there is nocorrelation between herbicide use and weed harmfulness for crop production. De novo expert design ledto bigger changes in practices and systems performances, compared to co-design with farmers, especially when innovative systems are designed for each farmer of a group. The evolution of sustainability of thesecropping systems was assessed with the multicriteria assessment model DEXiPM and again morechanges, often positive, were found with the design methods (i) and (ii). However, only a few innovativecropping systems designed with method (iii) were able to reduce weed harmfulness for production whileenhancing sustainability, thanks to major changes planned in crop sequences (winter wheat reductionand sugarbeet removal), after ten years of step-by-step design. These results illustrate differences andcomplementarities of these design methods.

International audience

Agroecosystems produce food and many other services that are crucial for human well-being. Given the scales at which the processes underlying these services take place, agricultural landscapes appear as appropriate spatial units for their evaluation and management. The design of sustainable agricultural landscapes that value these services has thus become a pressing issue but faces major challenges stemming from the diversity of processes, their interactions and the number of scales at stake. Agricultural landscape modelling can provide a key contribution to this design but must still overcome several difficulties to offer reliable tools for decision makers. Our study aimed at shedding light on the main scientific and technical difficulties that make the building of landscape models that may efficiently inform decision-makers a complex task, as well as translating them in terms of challenges that can be further investigated and discussed. We examine current issues and challenges and indicate future research needs to overcome the scientific and technical obstacles in the development of useful agricultural landscape models. We highlight research perspectives to better couple landscape patterns and process models and account for feedbacks, integrate the decisions of multiple stakeholders, consider the spatial and temporal heterogeneity of data and processes, explore alternative landscape organisations and assess multiobjective performance. Coping with the issues and challenges discussed in this paper should improve our understanding of agroecosystems and give rise to new hypotheses, thereby informing future research.

Pour tester la robustesse des stratégies innovantes de gestion des adventices, le changement climatique a été abordé par une approche de simulations climatiques régionalisées. D'abord, nous avons vérifié que le protocole de régionalisation dynamique mimait correctement le climat observé sur la période 1980-2016. Ensuite, ce protocole a été appliqué à deux trajectoires de forçage radiatif (RCP4.5 et RCP8.5) définies pour l'exercice d'intercomparaison des modèles climatiques globaux (CMIP5) afin d'évaluer l'incertitude associée aux émissions de gaz à effet de serre attendue sur la deuxième moitié du 21 e siècle. Enfin, nous avons comparé des systèmes de culture existants et prospectifs, en terme de gestion de la flore adventice et de son impact sur la production agricole et la biodiversité, avec ces trajectoires climatiques. Pour cela, 44 systèmes de 5 régions ont été simulés avec le modèle de dynamique de la flore adventice FLORSYS. Nos résultats montrent que les températures de surface augmentent en moyenne de ~4 °C en fin de siècle pour la trajectoire RCP8.5. Face à ces changements climatiques, trois types de systèmes de culture ont été identifiés : ceux dont la nuisibilité des adventices pour la production (1) diminue ; (2) augmente, particulièrement avec la trajectoire RCP8.5 sur la période 2069-2099 ; (3) est moyenne mais dont la contribution des adventices à la biodiversité augmente. Ces travaux identifient les leviers à prioriser pour définir des systèmes de culture innovants et robustes face au changement climatique. To evaluate the resilience of innovative weed management strategies, the impact of climate change wasinvestigated with a regionalized simulation approach. First, we checked that the protocol for dynamicregionalisation correctly mimicked the climate observed over 1980-2016. Then, the protocol was appliedto two periods (2010-2040 and 2069-2099). Finally, we compared existing and prospective croppingsystems in terms of weed management and impacts on crop production and biodiversity, with these twoclimate trajectories. To do so, 44 cropping systems from 5 regions were simulated with the weed dynamicsmodel FlorSys. Our results show that surface temperature will increase in average by approx. 4°C at theend of the century with the RCP8.5 trajectory. Three cropping system types were identified in responseto these climate changes, those whose weed harmfulness for crop production (1) decreased,(2) increased, particularly with trajectory RCP8.5 from 2069-2099, (3) was average but whose weedcontribution to biodiversity increased. The study allowed identifying the management levers essential forinnovative cropping systems that are robust relatively to climate change.

Crop diversification represents a key lever to support the development of sustainable agri-food systems. Knowledge on trade-offs and carry over effects from different crop diversification strategies is essential to inform agricultural stakeholders of potential costs and benefits. This knowledge is limited by existing data and performance measures predominantly focused on single crops, rather than complete rotations. Moreover, sustainability performance indicators are often used for assessment purposes, rather than supporting stakeholder learning and actions. A new set of 32 indicators was developed to address these needs, and used to evaluate the environmental, economic and social sustainability of the diversified agricultural systems highlighted in the case studies, which are often characterized by data availability constraints. This approach was tested in France, Germany and Italy to determine a critical ex-post diagnosis of the existing systems, and for the assessment of ex-ante innovative scenarios. The results will be used to support these case studies in the identification and design of more sustainable agricultural systems. Although the framework is based on feasible and proxy indicators, the assessment outcomes have allowed local actors to reflect on the effects generated by the implemented crop diversification strategies. Key issues include trade-offs occurring between optimizing economic and environmental performance.

There is strong social and political pressure to reduce pesticide use in European agriculture. Evaluating the sustainability of cropping systems is a complex task due to the conflicting objectives underlying its economic, social and environmental dimensions. Multi-criteria assessment of different Integrated Pest Management (IPM) scenarios and evaluation of the most sustainable options at regional, national and European level is essential. Within the EU Network of Excellence ENDURE, two expert-based surveys were conducted (i.e. interviews), where experts from four European regions (northern region, Denmark and The Netherlands; central-eastern, Tolna and Békés counties in Hungary; south-western, Ebro Valley in Spain; southern, Po Valley in Italy) determined which are the main current maize-based cropping systems (MBCSs) in their region and proposed innovative IPM-based systems. The DEXiPM® (DEXi Pest Management) model for arable cropping systems was used to evaluate and compare the economic and environmental sustainability of these systems. The social sustainability was evaluated by adapting indicators of this model to the specificities of maize systems. The assessments showed that all innovative rotated MBCSs proposed in the four regions can have a higher environmental sustainability than and maintain the same economic sustainability as current rotated systems. These cropping systems are thus acceptable for testing under “real” field conditions. Only the innovative continuous maize system proposed in the central-eastern region was both economically and environmentally more sustainable than the current system. All innovative systems had a positive impact on work safety but according to local expert opinion producers and consumers are not ready to implement them or to accept their higher-priced products, with the exception of consumers in the northern region. These results suggest the need for European and regional policies to encourage the adoption of innovative rotated MBCSs that have positive agronomic and environmental impact through IPM implementation. The major constraints that inhibit this adoption were predominantly relating to (1) the lack of access that farmers have to the practical knowledge needed to effectively manage these systems and (2) the insufficient consumer awareness and acceptance of product improvements associated with IPM. To overcome these constraints supportive policy environments, well-functioning knowledge management systems (including good farmer support networks) and effective marketing is required