Assessment of Physicochemical and Microbiological Properties of Soil from Organic Vegetable Farms in Bangladesh

Background. Organic fertilization is the key input for agro-ecological farming, which consistently keep the soil healthy, fertile and productive. In order to assess the sustainability of organic farming, the physicochemical and microbiological properties of soils from organic, semi-organic and conventional farms cultivating tomato, potato and bottle gourd were analyzed in this study. Method. The physicochemical parameters including content of P, K, and other major and micro-minerals as well as organic matter, presence of heavy metal, etc. and the microbial populations including quality parameter (total aerobic bacteria, coliform bacteria, indicator Escherichia coli.), other common pathogens (Klebsiella sp., Salmonella sp., and Shigella sp.) and soil beneficial microorganisms including Pseudomonas sp., Bacillus sp., Rhizobium sp., Azotobacter sp., Phosphobacteria and phosphate solubilizing fungi, Tricoderma sp. and total fungal population were determined using standard microbiological plate count methods followed by biochemical and API immunoassay techniques. Results. The results revealed that organic matter, available N and P content were always found higher in organic fertilizer farming than that of semi-organic and chemical fertilizer farming. The soil beneficial microorganisms, soil quality microorganisms, and pathogens content was found higher in organic fertilizer farming compared to other two methods of farming. The total input in production of tomato, potato and bottle gourd in organic fertilizer farming was found lowest compared to semi-organic and chemical fertilizer farming. Conclusion. The results of this study demonstrated that the use of properly composted organic fertilizers only can ensure safe crop production, increase soil health, improve agro-ecology, but decreased yield compared to chemical farms.