Biological indicators of soil health under soybean cultivation as affected by mycorrhizal application and seed treatment in typical chernozem

Introduction

Soybean has a strong impact on soil biological processes by interacting with microorganisms. Using arbuscular mycorrhizal fungi (AMF) and bacterial inoculants improves nutrient uptake and soil biological activity. However, the combined effects of these treatments with chemical seed treatment on soil health indicators in chernozem soils under intensive farming have not been studied enough.

 

Materials and Methods

The research was carried out on typical chernozem after maize for silage and soybeans. All variants of the experiment were created under uniform mineral fertilization (N₆₀P₆₀K₆₀).

The experimental design included the following treatments:

• Control – mineral fertilization only, without seed treatment, arbuscular mycorrhizal fungi, or inoculation;
• Chemical seed treatment – mineral fertilization with seed treatment (Maxim XL, 1.0 l/t);
• Mycorrhizal treatment – MycoApply (4.0 g/ha) combined with seed treatment (Maxim XL, 1.0 l/t) under mineral fertilization;
• Combined biological treatment – MycoApply (4.0 g/ha) + HiStick inoculant (400 g/ha) with seed treatment (Maxim XL, 1.0 l/t) under mineral fertilization

The number of microorganisms capable of ammonification, amylolysis, oligotrophy, pedotrophy, phosphate mobilization, and actinomycetes was assessed. The functional indices of soil health were evaluated using the coefficients of mineralization-immobilization, organic matter transformation, oligotrophy, and pedotrophy.

 

Results and Discussion

The control samples showed fairly high soil biological activity, which suggested a substantial presence of ammonifying microorganisms. The presence of numerous oligotrophic and pedotrophic microorganisms suggests the stable organic matter pools were frequently used. The limited quantity of actinomycetes present suggests a reduced rate of humification and carbon stabilization.

The application of Maxim XL led to a broader decrease in microbial populations, especially affecting oligotrophic and pedotrophic microorganisms. Lower values for the coefficient of organic matter changes suggest a dampening of microbial actions involved in breaking down organic residues.

Integrating MycoApply with a chemical seed treatment helped recover some microbial populations and improved functional measures when contrasted with seeds that only received the chemical treatment. More phosphate-mobilizing microorganisms showed up, meaning there was more phosphorus available.

The biological treatment, which included MycoApply with HiStick and Maxim XL, showed the best microbial response, as compared to other treatments. The presence of mycorrhizal fungi and bacterial inoculant lessened some of the negative aspects associated with chemical seed treatment. We found that microbial numbers and activity were greater than with just the chemical treatment by itself. Even though the microbial levels did not quite get back to where they started, this treatment did make the microbial community more resilient and stable when a lot of fertilizer was used.

 

Conclusions

In a common chernozem soil, various seed treatments for soybean farming caused noticeably different reactions in the biological markers for soil health. The application of chemical seed treatments independently led to a reduction in both microbial activity and the processes involved in organic matter transformation. In contrast, applying arbuscular mycorrhizal fungi, especially when paired with bacterial inoculation, somewhat lessened these problems and contributed to more even soil microbial activity. The findings indicate that biological methods can sustain soil health and ecosystem functions in soybean-based agroecosystems under conditions of global change.