Towards a Theory of Smallholder Agronomy in Africa: Complexity, Heterogeneity, and Evidence Synthesis from Nigerian Farming Systems

This study proposes and develops a theory of smallholder agronomy specific to African farming systems, using Nigerian case studies to construct and validate a theoretical framework that addresses the complexity and heterogeneity that distinguish smallholder agronomy from the commodity agriculture contexts in which most agronomic theory was originally developed. Mainstream agronomic theory assumes relatively homogeneous field conditions, rational profit-maximising farmers, and well-functioning input and output markets, all of which are systematically violated in Nigerian smallholder contexts. The result is a persistent theory-practice gap where academic agronomic knowledge inadequately guides practice and policy. This study applies complex adaptive systems theory, heterogeneity modelling, and evidence synthesis from the Nigerian agronomic literature to construct a Smallholder Agronomy Theory that incorporates six distinctive features: production heterogeneity at multiple scales, risk-aversion as a rational management principle, embedded social learning as a technology diffusion mechanism, indigenous knowledge as a parallel epistemic system, livelihood portfolio effects on agronomic decisions, and adaptive management under deep uncertainty. Empirical grounding uses novel analysis of 15 years of on-farm agronomic trial data from IITA Nigeria programme, the LSMS-ISA agricultural data, and original qualitative fieldwork with 120 farmers and extension workers across all geopolitical zones. Findings validate the theory's predictions about management heterogeneity and evidence its superiority over standard agronomic assumptions in predicting actual farmer management behaviour. The study recommends the Smallholder Agronomy Theory as the conceptual foundation for re-designing Nigerian agricultural research and extension systems.

Keywords: smallholder agronomy theory, African farming systems, complexity, heterogeneity, Nigeria.