The study found that using 30 tons of farm yard manure (FYM) and a specific combination of inorganic fertilizers led to higher maize grain yields. Bio-fertilizers did not significantly affect grain yield alone, but when combined with 10 tons of FYM and specific inorganic fertilizers, they resulted in the highest benefit-cost ratio and net return. The recommended approach for maximizing maize yield in low to medium fertile soils is to use 150:100:50 kg N-P2O5 and K2O/ha of inorganic fertilizers, along with 10 tons of FYM/ha and the bio-fertilizer Azospirillum with PSB. Increasing the FYM application to 30 tons/ha can further enhance grain yield.