Farmers worldwide use agrochemicals and biological inputs to fertilize fields, manage pests and diseases, and promote plant growth. However, there is still limited field-based evidence on the extent to which biological inputs function as substitutes, incremental complements, or alternatives to agrochemicals in key farming practices. This study presents preliminary results on the use of synthetic and biological inputs for the most common practices employed by large soybean farmers in central Brazil. We combined literature review, regulatory data on registered biological products, and in-person interviews with farmers and market experts. Our results show that, in most practices, biological products are adopted alongside the continued use of synthetic inputs, in some cases reducing the frequency or dosage of chemical applications. Inoculants based on nitrogen-fixing bacteria already substitute mineral nitrogen fertilization in soybean, while biosolubilizers and plant activators are used incrementally to enhance the efficiency of chemical fertilizers. Bioinsecticides and biofungicides are predominantly employed as alternatives within spray programs, especially in preventive or early interventions, thereby reducing the number of conventional pesticide sprays. Bionematicides emerge as the main biological tools used as substitutes for synthetic nematicides in preventive treatments, whereas biological herbicides are not yet available on the market. Field evidence presented in this study showed that farmers adopt biological products in diverse ways, including as substitutes, incremental, or alternatives to chemical products, depending on the technologies available. These findings provide a more nuanced understanding than the common views that, on one hand, biological inputs simply complement rather than substitute chemical products, and on the other, that biological solutions can fully substitute synthetic products. As environmental and economic implications, we conclude that biological inputs can underpin trajectories towards more regenerative management in large-scale soybean systems, even when synthetic inputs remain part of the production matrix.