Impact of Combining Bio-Inoculants along with Inorganic Fertilizers on Soil Biological Characteristics in Transplanted Rice (Oryza sativa L.) Crop

A field experiment was carried out during the Kharif season in the year 2022 to assess the impact of inorganic fertilizers along with Bio-inoculants on soil biological properties in rice (Oryza sativa L.). The experiment consists of seven treatments viz., T1 Control, T2 100% RDF (150, 60, 40 N2, P2O5, K2O kg ha-1), T3 80% RDF + 10 kg BGA ha-1 Soil application + PSB (Phosphate solubilizing bacteria) 3kg/ha, T4 60% RDF + 10kg BGA ha-1 Soil application + PSB, T5 80% RDF + 500kg Azolla ha-1 Soil application +PSB, T6 60% RDF + 500kg Azolla ha-1 Soil application +PSB and T7 10kg BGA ha-1 Soil application + 500kg Azolla ha-1 Soil application + PSB were comprised in Randomized Block Design with three replication. The incorporation of inorganics, Azolla PSB, and BGA (bio-inoculants) actively activated microbial activities, resulting in a greater increase in the populations of total bacteria, actinomycetes, and fungi was observed throughout all growth stages, regardless of the treatments applied, when compared to their initial densities. This phenomenon supports the notion of a stronger rhizosphere effect. This trend aligns with the rise in organic carbon content. Moreover, soil dehydrogenase, alkaline phosphatase activities, along with microbial biomass carbon, displayed an upward trend in tandem with the progressive growth phases of the rice plant.