Maize (Zea mays L.) is one of the most important cereal crops in Ethiopia. However, its yield is lower than its potential mainly due to low soil fertility problems caused by continuous cultivation, limited use of organic and inorganic fertilizers, erosion, and leaching. Therefore, this field experiment has been conducted to optimize brewery sludge and blended NPS fertilizer rates to harness the maximum productivity potential of maize in North Mecha District, northwestern Ethiopia. The experiment was designed in a factorial arrangement of three levels of brewery sludge (0, 10, and 20 t ha−1) and four levels of blended NPS fertilizer (0, 50, 100, and 150 kg ha−1) in a randomized complete block design with three replications. The analysis of variance showed that the main effects of the blended NPS fertilizer had significant effects on the ear length, number of kernels per row, stover yield, and 1000‐kernel weight. Their interactions also had a significant effect on leaf area, leaf area index, aboveground dry biomass yield, grain yield, plant height, number of ears per plant, number of rows per ear, number of kernels per row, number of kernels per ear, and harvest index. Accordingly, the combined application of 10 t ha−1 brewery sludge and 100 kg ha−1 blended NPS fertilizer resulted in the highest grain yield (9163.4 kg ha−1), net benefit (145,590.1 ETB [Ethiopian Birr] ha−1), and marginal rate of return (3789.30%) of maize. Thus, this treatment can be tentatively recommended for the North Mecha district.
