Empirical Analysis of Cassava Productivity and Market Surplus Behaviour Among Smallholder Farmers in Edo State, South South Nigeria

Cassava production in South South Nigeria underpins both household food security and industrial raw material supply chains, with Edo State hosting a growing cassava processing industry dependent on reliable smallholder supply. Despite this strategic importance, empirical analysis of the productivity drivers and market surplus behaviour of cassava farmers in Edo State remains limited. This study empirically analysed cassava productivity and market surplus behaviour among smallholder farmers in Edo State using primary data from 195 farming households. A two-stage model was applied: the first stage estimated the determinants of cassava output using a production function model, while the second stage estimated market surplus determinants using a Heckman selection model to account for the censored nature of surplus sales. Results revealed that fertiliser application, improved variety adoption, and extension contact were the most significant positive determinants of cassava output. Market surplus was positively influenced by road access, off-farm income, and household head education, but negatively affected by household size and food consumption demand. Distance to processing facilities significantly reduced surplus volume, suggesting the importance of spatial value chain linkage. The study recommends co-locating cassava processing facilities with production clusters in Edo State and strengthening improved variety distribution in key production zones. Keywords: cassava, productivity, market surplus, Edo State, Heckman selection model.