Enhancing Black Soil Fertility and Microbial Community Structure via Microbial Agents to Reduce Chemical Fertilizer Dependency: A Strategy to Boost Maize Yield

Years of employing the “one-shot” fertilization practice have led to low nutrient utilization efficiency and the degradation of soil structure in the black soil region during crop cultivation. Replacing a portion of chemical fertilizers with microbial agents can effectively solve these issues. In this study, we conducted a field plot experiment comparing eight different treatment combinations to investigate the effects of combining microbial agents with varying amounts of chemical fertilizers on black soil nutrients, soil ecology, and maize yield. The high-throughput absolute quantification 16S rRNA sequencing method was utilized to further investigate the effect of the various treatments on soil bacterial community structure and elucidate the interactions between environmental factors and microbial communities. The results showed that MC80 increased maize yield by 5.76% compared to RC, with an input–output ratio of 1:1.58. Additionally, soil nutrient levels in MC80 were higher than those in RC, increasing nutrient utilization efficiency, activating soil nutrients, and enhancing soil fertility. Meanwhile, the absolute quantification data of bacteria also indicated the highest bacterial abundance and diversity in MC80 samples. Among these, Acidobacteria was the main contributor to the changes in the bacterial community, showing significant enrichment in MC80. RDA and Spearman correlation analyses indicated that soil nutrients are the key factors influencing the bacterial community in this ecosystem, while the microbial community plays a crucial role in nutrient transformation processes. Principal component analysis (PCA) was used for comprehensive evaluation and ranking. Overall, the soil under the MC80 treatment was most conducive to microbial survival and maize growth. This study provides a high-yield and sustainable fertilization method for maize and offers a theoretical basis for applying microbial agents in sustainable agriculture.