Seedling mycorrhization increases maize yield without altering soil properties: A field study

Functional microorganisms play key roles in sustainable agriculture, and seedling technologies leveraging the priority effect are vital for unlocking the potential of these microorganisms. However, there is still a lack of systematic assessments of microbial seedling technologies on yield and soil properties under field conditions. This study employed mycorrhizal and bio-organic seedling cultivation (MSC and BOSC) to explore the effects of arbuscular mycorrhizal (AM) fungi, mineral fertilizers, organic fertilizers, and other plant-beneficial microbes (PBMs) on maize yield and soil properties in the field. The results showed that AM fungi significantly increased maize yield by mediating phosphorus nutrition and improved agronomic traits such as ear length, ear diameter, and grain number per ear. However, AM fungi had no significant effect on soil properties, including pH, electrical conductivity, total nitrogen, soil organic carbon, fungal diversity, and bacterial diversity. Inoculation with PBMs (excluding AM fungi) at the seedling stage might not maintain the rhizosphere niche in the field, and therefore did not effectively promote maize growth. In addition, adding mineral and organic fertilizers to the seedling medium made the seedlings stronger, but had a limited effect on the yield. For economic reasons, we recommend that mycorrhizal seedling cultivation without addition of fertilizers. Our research provides important implications for the use of functional microorganisms in agriculture.