Mixed crop–livestock systems have a crucial role to play in meeting the agricultural production challenges
of smallholder farmers in sub-Saharan Africa. Sweet potato is seen as a potential remedial crop
for these farmers because of its high productivity and low input requirements, while its usefulness for
both food and feed (dual-purpose) make it attractive in areas where land availability is declining. In this
paper, we develop and apply a ‘minimum-data’ methodology to assess ex ante the economic viability of
adopting dual-purpose sweet potato in Vihiga district, western Kenya. The methodology uses and integrates
available socio-economic and bio-physical data on farmers’ land use allocation, production, and
input and output use. Spatially heterogeneous characteristics of the current system regarding resources
and productivity are analyzed to assess the profitability of substituting dual-purpose sweet potato for
other crops currently grown for food and feed. Results indicate that a substantial number of farmers in
the study area could benefit economically from adopting dual-purpose sweet potato. Depending on
assumptions made, the adoption rate, expressed as the percentage of the total land under adopting farms,
is between 55% and 80%. The analysis shows that the adoption rate is likely to vary positively with the
average total yield of dual-purpose sweet potato, the harvest index (the ratio between tuber and fodder
yields), the price of milk, and the nutritional value of available fodder. This study demonstrates the usefulness
of the minimum-data methodology and provides evidence to support the hypothesis that dissemination
of the dual-purpose sweet potato could help improve the livelihoods of smallholder farmers
operating in mixed crop–livestock systems in east Africa.