Public thesis defense of Noé Vandevoorde

Three tools for the reduction of pesticide impacts:
a case study in the Province of Luxembourg

How can we reduce the negative health and environmental impacts of pesticides while supporting productive agriculture? This PhD research has developed three practical tools —spanning policy, agronomy and environmental science— to guide more sustainable farming practices. From refining pesticide risk indicators for EU-wide policy to optimising crop rotations and leveraging cover crops for groundwater protection, the work bridges field-level action with territorial-scale strategies. Join us to explore how these innovations can facilitate the transition towards lower-input, ecologically sound farming systems.

The presentation will be delivered in French. All are welcome to join for drinks after the defence.

The public defence can also be followed online: Public Thesis Defense – Noé VANDEVOORDE

This dissertation develops three practical tools to reduce the health and environmental impacts of pesticide use, supporting diagnosis, design and decision-making from field to territorial scales. Combining regulatory, agronomic and environmental perspectives, the deliberately pluralistic approach aims to guide more sustainable agricultural practices, with applications in the Province of Luxembourg and beyond.

First, the Pesticide Load Indicator is adapted to support taxation, policy evaluation and farm-level decisions at EU-wide scale, by promoting lower-risk pesticide use. Building on Danish and British versions of the indicator, the proposed modifications incorporate updated toxicological and environmental hazard data as well as improved normalization and weighting procedures.

Second, crop sequence diversity and agronomic optimisation are addressed as core strategies of integrated pest management. Using detailed 2015–2020 field-level IACS data, two existing crop sequence indicators were refined to better capture organic and mixed crop-livestock systems by including temporary grasslands and fodder crops. The results show a strong link between organic certification, temporary grasslands and more diverse, resilient rotations, with implications for both territorial assessments and on-farm preventive strategies.

Third, the agri-environmental role of cover crops is investigated in a greenhouse experiment involving 18 pesticides ingredients across three treatments: bare soil, thin cover crop and thick cover crop. Results show thin cover crops retain residues in topsoil and reduce leaching, while thick cover crops promote degradation in the rhizosphere, especially for compounds with low to high water solubility (s⩽1400mg/L) and low to moderate soil mobility (Koc⩾160mL/g). These findings highlight the multifunctionality of cover crops in enhancing soil resilience and protecting water quality.

Together, these tools offer actionable insights to reduce pesticide dependency and negative impacts. While no single measure can transform high-input agriculture alone, their combined use (integrated into a systemic, stakeholder-driven policy mix) can support a transition toward more sustainable and ecologically sound farming systems.

Jury members

Supervisors:
Prof. Philippe V. BARET : UCLouvain
Prof. Yannick AGNAN : UCLouvain

Other jury members:
Prof. Frédéric GASPART : UCLouvain ; Chairperson
Prof. Pierre BERTIN : UCLouvain ; secretary
Prof. Per KUDSK : Aarhus University (Danemark)
Dr. Lionel ALLETTO : INRAE Toulouse (France)