This study aims to evaluate yield improvement in Tanzanian smallholder farm systems through a Bayesian hierarchical model. A Bayesian hierarchical model was employed to analyse data collected from Tanzanian smallholder farms. This model accounts for both farm-level and field-level variability in yield measurements. The analysis revealed significant variation in yield across different fields within the same farm, indicating that site-specific interventions could lead to improved yields. The Bayesian hierarchical model provided a robust framework for assessing yield improvement by accounting for spatial heterogeneity. Further research should focus on implementing targeted interventions based on field-level data to maximise yield improvements in smallholder farming systems. Bayesian Hierarchical Model, Yield Improvement, Smallholder Farming, Tanzania The empirical specification follows $Y=\beta_0+\beta^\top X+\varepsilon$, and inference is reported with uncertainty-aware statistical criteria.