Empirical Analysis of the Yield Gap Between Research Station and Farmer Field Performance of Maize in the Guinea Savanna

The yield gap between what is achievable under controlled research conditions and what farmers actually obtain represents one of the most important productivity challenges in Nigerian cereal systems, and characterising the gap and its principal causes for maize in the Guinea savanna provides evidence for targeted intervention. This study empirically analysed the maize yield gap in the Guinea savanna zone of Kwara and Kogi States, North Central Nigeria, comparing yields across 80 farmer-managed fields with attainable yields from 12 research station trials conducted over the same seasons. A yield gap decomposition methodology drawing on water-limited potential yield simulation using CERES-Maize model was employed alongside structured farmer management assessment interviews. Official meteorological data from three stations were used for model parameterisation. The analysis revealed a mean farmer yield of 2.14 tonnes per hectare compared to a simulated water-limited potential of 6.38 t ha-1, representing a yield gap of 4.24 t ha-1. The yield gap decomposition attributed 41 percent to suboptimal nitrogen management, 24 percent to delayed planting relative to rainfall onset, 18 percent to inadequate weed management, and 17 percent to variety choice and other factors. Farms with extension contact produced 38 percent higher yields than non-contact farms. The study fills a gap in Guinea savanna yield gap quantification and recommends a multi-entry point integrated agronomy support programme targeting the nitrogen and planting date components as the highest-impact yield gap closure priorities.

Keywords: yield gap, maize, Guinea savanna, CERES-Maize model, extension contact