Abstract. Full Text is available at: https://doi.org/10.1080/20421338.2016.1257537Smallholder farmers are reluctant to risk investing in fertilizers. To understand how risk is perceived and how economic returns are distributed before the decision to invest in fertilizer use is made, needs a systematic approach using localized applications. This study assesses the profitability and net return variability of fertilizer micro-dosing (MD) in the sub-humid rain-fed maize (Zea mays L.) farming system in Tanzania. Useful data was gathered from a household baseline survey, water and nutrient limited calibrated yields, marginal costs and yields from farmers’ field trials, along with other information from expert and historical data. Crop yields, crop prices and prices for key production inputs (mainly fertilizer) were simulated for the net economic return distributions for maize under different fertilizer MD rates using the Economic and Nutritional Impact Assessment Model (FARMSIM), which is supported by Simulation and Econometrics to Analyse Risk (SIMETAR). The results show relative differences in stochastic returns between water and nutrient limited (without fertilizer MD) and with fertilizer MD scenarios. Farmers are likely to adopt fertilization technologies if best agronomic practices are promoted through farmer groups and field schools, fertilizers are re-packaged into small quantities for ease of purchase and access, and the coverage of subsidized fertilizers is increased.