Assessing the impact of nature-based solutions on soil health in sub-Saharan Africa through farmer-centred methods

Abstract Soils underpin many ecosystem services, including food production, through functions such as organic matter decomposition. These functions are increasingly threatened by soil degradation, especially in climate-vulnerable regions, such as sub-Saharan Africa, where unstable soils are prone to severe erosion. As soils continue to degrade, farmers face multiple challenges; they cannot afford accurate tests to assess soil, their livelihoods are constrained by demand for food, fuel and water, and competition for valuable resources hampers farming. Hence, there is a pressing need for accessible tools to assess soil health and methods to provide tailored advice on resilient, climate-smart agricultural management and optimal use of resources. This narrative review offers a comprehensive overview of key issues and potential solutions. We highlight tools and approaches that can support farmers to improve soil and secure livelihoods. Practical indicators and field-ready tests are evaluated, with examples from Ethiopia, but tailored to support farmers and advisors across sub-Saharan Africa and other developing countries. A wide range of tests are reviewed, including physical, biological, chemical, function and service-related tests, drawing on scientific and farmers knowledge. Science-based tests require expertise, equipment and incur costs, while locally-derived tests are affordable and seamlessly applicable. We also review Nature-based Solutions for improving soil quality, and assess them against factors such as labour, costs, and crop production. There is no single universally applicable practice; suitability depends on farmers’ priorities and circumstances. Therefore, we explore predictive methods—mechanistic, process-based soil models, data- and knowledge-driven Artificial Intelligence and systems models—to simulate the impact of practices on soil and farm dynamics. Promising approaches include hybrid approaches assimilating data, physics and knowledge through digital soil mapping. Overall, this review emphasizes the need to empower farmers with accessible tools and methods to harness Nature-based Solutions, build climate resilience and secure sustainable futures for generations ahead.