Effect of social capital dimensions on collective action among smallholder potato farmers in Kenya: A partial least squares structural equation modelling analysis

Social capital is widely recognised as a determinant of smallholder farmers' capacity to engage in collective institutional arrangements. Yet the structural mechanisms through which its dimensions interact remain underexplored in sub-Saharan Africa. This study examines how seven social capital dimensions (trust, networks, reciprocity, group membership, decision-making, market information, and institutional infrastructure) interact to shape collective action capacity, the behavioural manifestation of social capital amongst smallholder potato farmers in Elgeyo Marakwet County, Kenya. Using partial least squares structural equation modelling (PLS-SEM) on survey data from 577 randomly selected smallholder potato farmers, the study tests fifteen hypothesised structural pathways amongst these dimensions. The measurement model demonstrates satisfactory reliability (composite reliability: 0.700–0.921) and convergent validity (AVE: 0.542–0.776). The structural equation modelling results reveal that trust is the primary driver of collective action capacity, operating both directly (β=0.241, p<0.001) and indirectly through network formation (β=0.571→β=0.390; mediated effect β=0.223, p<0.001). Notably, reciprocity (β = -0.103, p < 0.001) and market information (β = -0.078, p < 0.01) negatively affect collective institutional action, suggesting substitution dynamics rather than complementarity in broker-reliant markets. Institutional infrastructure exhibits a negative relationship with networks (β = -0.084, p < 0.01), consistent with crowding out between formal and informal coordination and governance channels. These findings suggest that linear additive models inadequately capture the dynamics of social capital formation, underscoring the need for trust-building interventions as a prerequisite for collective institutional participation in smallholder farming systems. Thus, this study recommends that cooperative development programmes embed deliberate trust-building processes, such as farmer-to-farmer dialogue, as a precondition for sustainable collective marketing