The Role of Irrigation over Rainfed Farming Systems in Improving Rice Productivity in Tanzania: Policy Insights From the National Sample Census of Agriculture

Abstract

Rice is central to Tanzania's food security and economic development; however, persistent yield gaps, exacerbated by climate variability, threaten to undermine production targets. This study examines the role of irrigation in boosting rice productivity compared to traditional rainfed systems using nationally representative data from the 2019/2020 National Sample Census of Agriculture. A stochastic simulation approach assessed yields by water source across major agroecological zones (AEZs) under two productivity thresholds: (i) the national benchmark (≤ 1.5 and ≥ 3.0 t/ha) and (ii) the global high‐yield benchmark (≤ 2.0 and ≥ 4.5 t/ha). The results show that irrigation significantly improves yields and reduces downside risk. Nationally, irrigated farms were far more likely to exceed both benchmarks; for the ≥ 4.5 t/ha threshold, they had an over fivefold advantage compared to rainfed systems. Gains were evident across most AEZs, except the Western AEZ, which faces climatic and water constraints. These findings underscore irrigation's role in narrowing yield gaps, strengthening resilience and driving inclusive agricultural transformation. The evidence supports prioritizing irrigation expansion alongside inclusive water governance and complementary innovations such as improved seeds and extension services, contributing to SDGs 1, 2, 8 and 13. Targeted investment in underserved AEZs should be central to Tanzania's agricultural policy agenda.