Organic Amendment Effects on Microbial Population and Microbial Biomass Carbon in the Rhizosphere Soil of Soybean

The aim of the study was to determine microbial populations and microbial biomass carbon in the rhizosphere soil of soybean cultivated under different organic treatments: plant compost (PC), vermicompost (VER), farmyard manure (FYM), and integrated plant compost (IPC). The serial dilution plate method was employed to enumerate the rhizosphere soil fungi and bacteria. Results showed that microbial populations and biomass carbon were affected by the application of organic amendments. Fungal population was the greatest in the VER plot for two crop cycles, whereas bacterial population was the greatest in the VER in the first crop cycle and FYM for the second crop cycle. Tukey's test at P <= 0.05 showed that change in microbial biomass carbon in the sites studied over time was significant, with the greatest in FYM. In our study, addition of organic amendments affected the soil physicochemical properties, which in return affected the rhizosphere microbial characteristics.