The widespread use of plant protection products (PPP) in agriculture may lead to their accumulation in soils and may pose risks to soil organisms, yet long-term monitoring data remain scarce. The recently adopted EU Soil Monitoring Law emphasises the need for systematic soil monitoring across Europe by 2028. In Switzerland, a methodological approach for PPP monitoring in soils has been developed since 2017 within the Swiss Action Plan for Plant Protection Products and integrated into the Swiss Soil Monitoring Network (NABO). The objective is to assess PPP occurrence and support the evaluation of potential effects on soil functions to eventually maintain long-term soil fertility. Preliminary work included substance selection, analytical method development, and a baseline survey of PPP residues at 126 Swiss agricultural sites. The highly sensitive multi-residue method covering 146 substances detected PPP residues at all sites. Variations in concentrations and detection frequencies were driven by both PPP application intensity and pedoclimatic conditions. Furthermore, residue diversity varied between cropping systems. These findings formed the selection of representative annual and perennial cropping systems in Switzerland for monitoring at three- to four-year intervals, reflecting their distribution, PPP use intensity, and residue patterns. Insights from this preliminary work support the assessment of environmental exposure and potential ecotoxicological risks of PPP residues in agricultural soils, contributing to their consideration in regulatory decision-making.