Smallholder farming systems in South Africa are characterized by significant variability in productivity and resource use efficiency. A multilevel regression model was employed to analyse data from 100 randomly selected smallholder farms across South Africa. The model accounts for both farm-level and district-level variations in productivity. The multilevel analysis revealed that access to irrigation significantly increased crop yield by an average of 25% compared to non-irrigated farms, with a confidence interval of ±4% Multilevel regression provides a robust framework for assessing cost-effectiveness in smallholder farming systems, highlighting the importance of resource management strategies. Farmers and policymakers should prioritise investment in irrigation infrastructure to enhance productivity and profitability. The empirical specification follows $Y=\beta_0+\beta^\top X+\varepsilon$, and inference is reported with uncertainty-aware statistical criteria.