Organic and inorganic fertilizer use and sorghum productivity in Tanzania’s rainfed farming systems using national sample census of agriculture data

Sorghum ( Sorghum bicolor L. Moench) is a drought-tolerant cereal that plays a vital role in food security and rural livelihoods in Tanzania’s rainfed farming systems. However, national productivity remains low (≈ 1.0 t/ha), largely due to poor soil fertility and limited adoption of fertilizer technologies. This study evaluated the contribution of organic and inorganic fertilizers to sorghum productivity and generated evidence to inform fertilizer policy and sustainable crop production. The study utilized nationally representative data from the 2019/20 National Sample Census of Agriculture (NSCA). Probability density functions (PDFs) and yield distribution analyses were employed to compare sorghum productivity across farms using no fertilizer, organic fertilizer, and inorganic fertilizer. Yield probabilities were also estimated to assess the likelihood of achieving key productivity thresholds. Organic fertilizer users achieved a mean yield of 1.38 t/ha, only slightly higher than non-users (1.30 t/ha), with considerable yield variability and limited improvement in the probability of exceeding the 2.0 t/ha benchmark. In contrast, inorganic fertilizer users recorded an average yield of 1.94 t/ha, representing nearly a 50% increase over non-users. Approximately 30% of inorganic fertilizer users exceeded the 2.0 t/ha threshold, while 18% achieved yields above 3.0 t/ha, compared with less than 5% among organic fertilizer users and non-users. These findings demonstrate the significant contribution of inorganic fertilizers to improving sorghum productivity under rainfed farming systems. However, maximizing productivity requires fertilizer use to be complemented by improved seed varieties and appropriate fertilizer application practices. The study recommends expanding access to inorganic fertilizers, strengthening extension services, and integrating nutrient management strategies to enhance sorghum productivity, food security, and climate resilience in Tanzania.