Isolation and Characterization of Beneficial Microorganisms in Organic, Semi-Organic and Conventional Fertilizer Treated Agricultural Field Soil and Comparison of Bacterial Richness

The effect of different farming systems on microbial communities in agricultural environment was investigated in the present study. Depending on the present farming trend, the microbial distribution in agricultural soils treated with organic, semi-organic and conventional fertilizers was analyzed. A total of 20 soil samples were collected from different types of agricultural fields of Bangladesh Agricultural Research Institute (BARI, Gazipur). Microorganisms playing beneficial roles in soil such as nitrogen fixation (e.g. Rhizobium sp., Azotobacter sp.), phosphate solubilization (e.g. Bacillus sp., Pseudomonas sp., Phosphobacteria) and auxin production (e.g. Pseudomonas sp., Serratia sp. and Bacillus sp.) were evaluated from each of the samples. The results revealed that agricultural fields treated with chemical fertilizers showed lower microbial count than that of organic fertilizer treated agricultural fields’ soil samples. In addition, organic fertilizers amended field soils have higher phytohormone (Auxin) activities, phosphate solubilization bacteria and other bacterial richness compared to chemical fertilizer applied field soil.