The study aimed to see what would happen if biochar, sugarcane sludge, and Enterobacter asburiae strain were used alone or together to improve the soil’s N and P availability and hybrid maize seed yield. An experiment with hybrid maize on alluvial soil (Fluvisols) collected in An Phu, An Giang, was carried out at the net house of the College of Agriculture, Can Tho University. The two-factor factorial experiment included: (i) four formulations of mixed materials and (ii) two levels of bacterial strains. The results showed that adding biochar or sugarcane sludge did not improve soil pH and N, P availability. However, the growth and yield of maize significantly increased when applying biochar or sugarcane press mud fertilizer. The inoculation with E. asburiae makes more N and P available in the soil, which helps hybrid maize grow and make more food. Of the three soil factors, available N is the most important in the predictive models for determining plant height (R2 = 0.73) and grain yield (R2 = 0.81). In addition, the combination of available N and P strengthens the interpretation of maize stem diameter (R2 = 0.83). The soil’s pH, N, and P availability were not improved by adding rice husk biochar or sugarcane sludge organic fertilizer separately or together. However, when these materials were used, corn growth and yield significantly increased.