Het potentieel van burgerwetenschap voor duurzame voedselproductie en -consumptie

Today's global food system is facing pressing challenges related to climate change, biodiversity loss, and resource depletion. Sustainable agriculture is at the core of addressing these issues, and it requires both technological innovations and societal transformation. While researchers and policymakers play a central role, there is growing recognition that citizens should also be involved in this transition towards more sustainable practices. A promising approach to bridge the gap between policy, science and society is citizen science - a form of public engagement in which non-professionals contribute to scientific research. This PhD thesis explores how citizen science can support sustainable agriculture through the case of "Soja in 1000 Tuinen" (Soy in 1000 Gardens), a large-scale citizen science project in Flanders (Belgium), by involving the general public in a local experiment in their own garden. This way, the project is situated at the intersection of agriculture, biology, behavioral science, and participatory research, offering novel insights into the design, implementation, and impact of citizen science in high-input agricultural contexts. Through participation, citizens are not only engaged as partners in agricultural research where they influence scientific outcomes, but also contribute to sustainability transitions through capacity building and behavioral change. Across four chapters, the thesis investigates how citizen science can support sustainable food systems, who participates and why, what design elements encourage long-term engagement, and whether participation affects sustainability intentions. The first chapter introduces the citizen science initiative "Soja in 1000 Tuinen", where over 1000 participants planted soybeans in their own garden in Flanders. The project was designed to collect empirical data on the local viability of soybean cultivation through nitrogen-fixing soil bacteria Rhizobia, while simultaneously educating participants on sustainable food choices and soil health. The chapter outlines the project's dual objectives: generating data relevant to agricultural researchers and engaging the public in sustainability science.<br />The second chapter dives into the participant demographics, as well as their motivations and dispositional variables, such as values and sustainability knowledge, using survey data. The study differentiates between initial and sustained participation, identifying factors that promote continued engagement over time. It was revealed that in our case study, a self-selection bias was present. Initially participants were typically broad-minded, environmentally conscious and knowledgeable individuals. Key drivers for sustained engagement on the other hand, included moral obligation and age. In the third experimental chapter, five intervention strategies were developed and tested using the Octalysis framework to evaluate their effect on participant retention: (1) regular email reminders (control group), (2) community building via online groups, (3) individual contribution framing, (4) social norm messaging, and (5) gamification (badges, progress bars). The results show that motivational design matters: community-based and gamified approaches as well as individual contribution framing were most effective in maintaining engagement. This chapter contributes to the growing body of literature on how to design citizen science projects that are both scalable and sustainable in the long term. The last empirical chapter examines how participation in the "Soja in 1000 Tuinen" citizen science project was associated with sustainability-related attitudes, moral obligations, intentions, and behaviors over one and a half years. Using repeated survey data and structural equation models (SEMs), the study tracked changes in food consumption and garden management domains across three timepoints. Results show that while participants' knowledge increased steadily, attitudes, moral obligations, and intentions - particularly for food consumption - declined over time, though garden management measures partially recovered. Moral obligation and attitude consistently predicted intentions, whereas subjective norms and perceived behavioral control played a minor role, and the structural relationships between predictors and intentions remained largely stable across timepoints. Despite high explanatory power for intentions, actual behavior changes were modest, highlighting the persistent gap between awareness, intention and action. Finally, the 6th chapter starts with results from the preceding chapters, reflecting on the implications for Flemish soybean production, the contributions to literature, limitations of the research and opportunities for future research. The chapter concludes by reflecting on policy implications. The results of this dissertation are useful for policy makers and researcher to further their knowledge on the use of citizen science.