Many paradigms on sustainable agricultural intensification adhere to a combination of different and complementary agricultural technologies. Whether such a paradigm survives in practice depends on how, and if, farmers combine these technologies on their fields. The main biophysical rationale for farmers to combine different technologies is the existence of reinforcing yield effects. But farmers may face constraints that lead to a socio-economic rationale for interrelationships in the application of different technologies that contradict the biophysical rationale. There is little evidence on how and under which conditions farmers combine different agricultural technologies. In this paper, we focus on integrated soil fertility management (ISFM) and investigate how the concept is put into practice in South-Kivu, eastern Democratic Republic of the Congo (DRC). ISFM necessarily includes the use of improved germplasm, organic inputs and mineral fertilizer, and strongly emphasizes the complementarities and synergies that can arise when these technologies are jointly applied. We investigate whether these different ISFM technology components are applied jointly, sequentially or independently, and whether that matters for the long term use of the technology. We use original survey data from 500 farms in two territories in South-Kivu. We combine a descriptive statistical analysis and a factor analysis to understand interrelationships in the application of ISFM technologies, and relate it to technology characteristics and the local context. We find that few farmers in the area have reached “full ISFM”, and that application of ISFM technologies occurs sequentially, rather than simultaneously. At plot level two subsets of technologies can be distinguished. The first subset is characterized by more resource-intensive technologies (row planting and mineral fertilizer). The second consists of less resource-intensive technologies (improved legume and maize varieties). These subsets behave as supplements rather than as complements, and adoption within and among each subset is more sequential than simultaneous. Generally, farmers adopt less resource-intensive technologies first, and then adopt more resource-intensive technologies. Our results imply that there is a disconnect between the theoretical arguments in the agronomic ISFM literature, and the actual patterns of ISFM application on farmers’ fields.