Effects of Powdered and Granular AMF on Maize Growth Under Low Fertilizer Conditions

Excessive fertilizer use drives soil degradation and resource waste. This study investigates how arbuscular mycorrhizal fungi (AMF) formulations (powder vs. granular) optimize maize (<i>Zea mays</i> L.) yield, soil microbiome, and economic benefits under 50% and 75% fertilizer reduction. Field trials showed that the AMF powder formulation under 50% fertilizer reduction (AP50) increased maize yield by 14.67%. This increase was associated with rapid root colonization (85.3%), enhanced phosphorus availability, and the recruitment of beneficial fungi such as <i>Mortierellomycota</i>. Granular formulation at 75% reduction (AG75) achieved 7.18% yield gain via sustained symbiosis. Fungal communities exhibited greater sensitivity to fertilization than bacteria (Chao1, <i>p</i> = 0.0094), with AMF suppressing <i>Fusarium</i> by 42% while enriching functional taxa (<i>Actinobacteria</i>, <i>Mortierellomycota</i>). Economic analysis confirms that AP50 (30,435 CNY/ha) and AG75 (26,954 CNY/ha) yield higher net profits, where CNY denotes Chinese Yuan. Powder formulations maximize immediate benefits in medium- to low-fertility soils, whereas granules support long-term soil health in high-organic systems, providing a precision strategy for sustainable agriculture.