The use of pesticides is increasingly debated due to unwanted side-effects on humans and the environment. To inform farmers how to reduce such side-effects, comparative assessments of risks and environmental impacts of different crop protection strategies are required. In the present study, crop protection scenarios with different treatment intensity (LOW, MEAN, HIGH) were analysed for five crops in Switzerland: rape seed, wheat, carrots, potatoes, and sugar beets. The MEAN and HIGH crop protection are based on the 50th and 75th percentile of the treatment frequency per pesticide category using a dataset from the Swiss agricultural environmental monitoring, while the LOW scenario represents a reduced treatment frequency, according to the guidelines of the label organization IP-SUISSE. The analysis was conducted with Life cycle assessment (LCA) and risk assessment (RA) method in parallel. LCA assesses average long-term impacts over the whole life cycle, while RA focuses on maximum effects in the short-term, which are site- and context-specific. For LCA, the transfer of pesticides into different environmental compartments was modelled with the model PestLCI. The aquatic and terrestrial ecotoxicity were assessed with USEtox V2.02 and ReCiPe 2016, respectively. The analysis of the LCA results was carried out in two steps: first, only the impacts of pesticides were analysed for the cultivation of 1 ha of crop, in order to ensure a comparability with RA results. Second, a full LCA was conducted (functional unit 1 kg fresh product), including the entire life cycle of the crop. The RA was conducted with the model SYNOPS. It allows a comparative evaluation of overall risks to the field-adjacent local environments and can be used for assessing individual treatments as well as entire treatment sequences. This study showed that a considerable reduction potential exists for pesticide treatment patterns, particularly for the situation with high treatment frequency. Only one or a few active ingredients dominated ecotoxicity impacts and risks. Avoiding these dominating active ingredients seems to be promising for mitigating ecotoxicological impacts. Furthermore, the study showed that it is necessary to consider all relevant environmental compartments and not to focus on water bodies alone. The parallel analysis of environmental impacts (LCA) and risks to the environment (RA) provided a more complete assessment and allows for a robust decision support.
