The role of fertilizers in Tanzania’s rice production: policy insights from the National Sample Census of Agriculture

Introduction Rice is a major staple and commercial crop in Tanzania, playing a vital role in ensuring food security, supporting rural livelihoods, and contributing to national economic growth. However, smallholder productivity remains constrained by suboptimal input use and agroecological variability. Among the strategies debated to improve yields is the use of fertilizers, both organic and inorganic, whose effectiveness varies with climate, soil type, and farming system. Methodology This study employed a non-parametric stochastic simulation approach to model the impact of fertilizer use on rice productivity using nationally representative data from the 2019/20 National Sample Census of Agriculture (NSCA). Farmers were grouped into three categories: non-fertilizer users, organic fertilizer users, and inorganic fertilizer users. Yield performance was simulated and evaluated against two benchmarks: the national threshold of 3.0 t/ha and the global standard of 4.5 t/ha. Simulations were stratified by Agroecological Zone (AEZ) and administrative region, including Mainland Tanzania and Zanzibar. Results Simulation results indicate that inorganic fertilizer users achieved the highest probabilities of exceeding both productivity thresholds: 28% for yields >3.0 t/ha and 11% for yields >4.5 t/ha. Organic fertilizer users followed closely with 26 and 10% probabilities, respectively. In contrast, non-fertilizer users showed significantly lower probabilities: 19 and 5%. Downside risk (the likelihood of yield falling below the threshold) was also lowest among inorganic users. Spatial differences were observed, with farms in Mainland Tanzania generally performing better than those in Zanzibar. Variability across AEZs further emphasized the influence of site-specific factors. Discussion The findings underscore that both inorganic and organic fertilizers significantly enhance rice productivity, although their impacts vary by region. Inorganic fertilizers have a more pronounced effect, particularly in minimizing downside yield risks. However, a one-size-fits-all strategy may be ineffective due to regional heterogeneity. Therefore, policies should prioritize region-specific fertilizer strategies, integrated soil fertility management (ISFM), input subsidy reforms, and strengthened agricultural extension services. These interventions can help advance climate-resilient rice production and contribute meaningfully to Sustainable Development Goals (SDGs) 2 (Zero Hunger) and 13 (Climate Action).