Comparing methods for designing innovative cropping systems aiming at sustainable weed management
Comparaison de méthodes de conception de systèmes de culture innovants pour la gestion durable des adventices
Résumé
Three 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, especially
when 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.
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 management
Three 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, especially
Cavan N., et al.
190 Innovations Agronomiques 81 (2020), 189-200
when 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.
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