Suboptimal land management practices are degrading soils and undermining food production. Sustainable land management (SLM) practices can improve soil and enhance yields. This study identifies variations in SLM uptake, characterising farmers most likely to use SLM practices, identifying when it makes economic sense for farmers to implement particular SLM practices and how long it takes before benefits exceed costs. Using questionnaire data from farmers in western Kenya, we undertake a cost-benefit analysis and analyse determinants of SLM practice use. SLM implementation varied between counties and SLM practice(s), with household and farm characteristics, and access to assets and advice, playing a key role. SLM practices with high upfront and maintenance costs (e.g., terraces and agroforestry) offer low benefitto-cost ratios for individual farmers who must also wait many years to break even on their investments. Nevertheless, over the policy-relevant time horizon considered (to 2030), Net present value can be positive. Simple SLM practices (manuring and intercropping) have low input costs and offer high benefit to cost ratios, providing a positive net present value up to 2030. Findings suggest that simple practices should be prioritised within policy to improve soil and increase yields. These should be supported by subsidies or other economic measures, facilitating uptake of practices such as agroforestry, which can provide wider societal benefits (e.g., improved water retention and carbon sequestration). Economic mechanisms could be augmented with support for agricultural innovation systems, improved monitoring of land management and yield relationships, and investment in climate and soil information services.