Improving Soil Health through Climate-smart Agriculture in Sub-Saharan Africa – The Essential Role of Farmers’ Knowledge

Soil health is key to building resilience into agricultural and food systems in sub-Saharan Africa (SSA), where climate change presents a major challenge and unsustainable land management practices have exacerbated land degradation. A suite of interventions labelled climate-smart agriculture (CSA) such as conservation agriculture (cover cropping, mulching, crop rotation, intercropping, minimum/zero tillage, crop residue management), soil and water conservation (contour planting, terraces and bunds, planting pits, and irrigation) and agroforestry are promoted in SSA to improve soil health but adoption among smallholder farmers remains low. A strong evidence base on the impacts of CSA interventions on soil health in different agro-ecosystems in SSA is lacking. This contributes to weak policies and institutional support as well as conflicting messages that farmers receive about CSA impacts, which limit their adoption and lead to disadoption. Farmers’ knowledge of their soils influences their land management decisions and is an important factor in the uptake of CSA interventions. Using a multi-method approach that combines conventional soil testing and farmers’ visual techniques, we examined the impacts of soil and water conservation techniques on soil health indicators in the East Usambara Mountains of Tanzania. The link between farmers’ soil knowledge and their land management decisions was also explored in a wider review of lessons from the African Highlands. Farmers’ observed changes in selected soil health indicators, which influenced their land management decisions did not always match results of conventional soil testing, highlighting the need for integrating farmers’ observational techniques and conventional soil testing for a more targeted and comprehensive assessment of soil health. A hybrid approach to soil assessment is outlined that could foster greater uptake of sustainable land management practices including CSA by farmers in SSA and should be proactively pursued by soil scientists to ensure that their efforts translate to actions by land managers.