Three tools for the reduction of pesticide impacts. A case study in the Province of Luxembourg.
(2025)
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- Abstract
- This dissertation explores strategies for mitigating the negative health and environmental impacts of pesticide use. It proposes three practical tools to support diagnosis, design and decision-making at various scales, from the field to the territorial level. The deliberately pluralistic approach combines regulatory, agronomic and environmental perspectives to address key dimensions of pesticide impacts. The aim of these tools is to inform more sustainable agricultural practices, with applications in the Province of Luxembourg and beyond. Firstly, a pesticide load (pl) indicator is developed to support policy instruments such as taxation, policy monitoring and farm-level decision-making. The goal is to promote the use of lower-risk pesticides. Based on the Danish and British adaptations of the pl, we propose five methodological updates integrating recent toxicological and environmental hazard data, refined normalisation procedures and statistically grounded weighting protocols. The resulting indicator, ranking active substances by their potential impact, offers a transparent and internationally transferable framework. Secondly, we examine crop sequence diversity and agronomic optimisation as foundational pillars of integrated pest management (ipm) in tools that can be used to assess cropping systems at a territorial level and guide preventive decisions at a farm level, with the aim of limiting input use. Using detailed, field-level data from the integrated administration and control system (iacs) database (2015–2020), we adapted and extended two existing crop sequence quality indicators to better account for organic and mixed crop–livestock systems, including multi-annual fodder crops and temporary grasslands. In southern Wallonia, our results demonstrate a strong association between organic certification and the inclusion of temporary grasslands and more diverse and resilient crop sequences. Conversely, the prevalence of fodder maize monocultures correlates with less favourable agronomic outcomes. Thirdly, we explore the curative agri-environmental role of cover crops in mitigating the persistence of pesticides in soil and their leaching into groundwater. A controlled greenhouse experiment was conducted with 18 active substances across three modalities —bare soil (control), a thin cover crops and a thick cover crops— to monitor how the substances behaved in relation to their physicochemical properties under the different covers. The findings revealed that thin cover crops reduced pesticide leaching by retaining residues in the topsoil, whereas thick cover crops enhanced degradation within the rhizosphere. These differentiated effects highlight the multifunctional role of cover crops in improving the resilience of agroecosystems and protecting water resources. Taken together, the tools developed in this dissertation provide actionable insights into reducing pesticide use and its negative health and environmental impacts. Although no single solution can address the systemic dependencies of Western ‘conventional’ high-input farming, a combined, context-sensitive use of these tools within a systemic policy mix can facilitate meaningful change. Advancing this transition will require a systemic and active involvement of all stakeholders —including farmers, advisers, upstream and downstream sectors, researchers, policymakers and consumers— to co-create an agriculture that is both productive and ecologically responsible.
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Vandevoorde, N. (2025). Three tools for the reduction of pesticide impacts. A case study in the Province of Luxembourg.