Overuse of pesticides is one of the main hanging issues which impede sustainable crop production. Despite a rapid growing body of research assessing the impact of agricultural diversification (practices/crop/ non-crop/ microorganism diversity) on the ecological perspective of the cropping system (e.g. ecosystem services and biodiversity), a synthesis on the agronomical impact is less documented. A few researches conducted on an experimental scale has proved that crop diversity can reduce agronomical input such as pesticides. However, those results are context-dependent, so it is hard to conclude on a broader view. Therefore, a quantitative analysis is missing about the relationship between crop diversity and pesticide use, on a large range of production situations. This study is focusing on depicting the relationship between two major components of sustainable cropping systems, i.e. crop diversity and pesticide use, based on the French DEPHY network dataset, including data from around 3,000 French commercial farms over ten years. Crop diversity is described using a combination of divisional methods, namely plant taxonomy (e.g. legume crop), ecological functional groups (e.g. nitrogen catching), agronomical functional groups (e.g. minor crop, cover crop, sowing season), and sale type (e.g. Farmers tend to use more pesticide on contracted crops: seed maize, etc.). Indicators from the domains of ecology and agronomy will be used to assess the crop diversity level. An analysis of the effect of preceding crop on pesticide use will also be conducted to test the crop diversity impact on a temporal scale, considering the variance caused by pedoclimate and cropping system characteristics. A reader-friendly summary of the Ph.D. target would be, an attempt to understand the complexity of “taking crop diversity as a tool to reduce pesticide”, during this period of time.