Synergistic Influence of Bacterial and Fungal Inoculum on Microbial Biomass Carbon, Phosphorus and Nitrogen

Background: Soil microbial biomass plays a crucial role in nutrient cycling, storing large amount of carbon, nitrogen, and phosphorus essential for soil fertility, while also driving organic matter decomposition and supporting plant nutrient uptake. Beneficial microorganisms like Azotobacter chroococcum and Serendipita indica have demonstrated plant growth-promoting properties by enhancing nutrient uptake, stress resistance, and microbial biomass. Their synergistic use aligns with sustainable agriculture practices, reducing dependency on chemical fertilizers and improving soil health. Materials and Methods: The study utilized cultures of S. indica and A.chroococcum grown in jaggery- based broth for bulk multiplication were made during the present study. Tests in the field were carried out during May–October 2023, with treatments: Control (C), T1 (A. chroococcum), T2 (S. indica), and T3 (combination). Microbial biomass carbon (MBC), Phosphorus (MBP), and Nitrogen (MBN) were estimated using fumigation extraction techniques. Statistical analysis was performed using ANOVA and Duncan’s Multiple Range Test at a 5% significance level. Results: The study revealed substantial increase in soil microbial biomass carbon (MBC), phosphorus (MBP), and nitrogen (MBN) in rice varieties PB 1121 and PB 1718 following treatment with S. indica and A. chroococcum. The study revealed significant increases in soil microbial biomass carbon (MBC), phosphorus (MBP), and nitrogen (MBN) with S. indica and A. chroococcum treatments in rice varieties PB 1121 and PB 1718. For PB 1121, MBC, MBP, and MBN increased by 67, 218, and 67.5%, respectively, with A. chroococcum treatment, while combined application increased the following by 122, 273, and 123%. Similarly, for PB 1718, A. chroococcum increased MBC, MBP, and MBN by 146, 54, and 148%, respectively, with combined treatment synergistically increased them by 213, 147, and 216% as compared to control. Conclusion: The co-inoculation of A. chroococcum and S. indica significantly enhanced soil microbial biomass carbon, phosphorus, and nitrogen compared to individual treatments or control. This synergistic effect supports nutrient cycling and sustainable agricultural practices by reducing chemical fertilizer use and improving soil fertility. The findings highlight the potential of microbial inoculants in developing bio-fertilizers and fostering long-term agricultural sustainability. The research highlights the importance of bio-fertilizers as a sustainable alternate to chemical fertilizers, which have detrimental effect on the environment and living beings. By demonstrating the synergistic benefits of A. chroococcum and S. indica in enhancing soil fertility, it highlights the potential to reduce chemical fertilizer dependency for farmers. The development of cost-effective, accessible, and easy-to-use bio-fertilizers stands with the urgent need for eco-friendly agricultural solutions.