Pesticides Contaminated in Rice Paddy Soil Affecting on Cultivated Microorganism Community

Abstract

It has been known for the diversified microbes living in the soil are basic indicators of changes in the ecosystem especially in paddy soil. The effects of continuous application of pesticides in rice field are widely discussed but still disregarded due to unclear and underestimated by the users and the chemicals also need time to accumulate and slowly affect the environment and health. The objective of this research was to understand the effects of pesticides on microorganism community in rice field. Both the numbers and the types of useful soil microorganisms including nitrogen fixing and common habituated microorganisms were compared in between using and not using chemical pesticides samples. The results showed that productivity of cultured microorganisms in the paddy applied with pesticides has dropped only slightly (approximately 9% reduction), however, more spore-forming Gram positive bacteria were detected. Additionally, increases in common microorganisms in the soil at a depth below than 20-50 cm were observed that could possibly be because of less pesticide availability there comparing to the surface of paddy soil. Although the changes in numbers and types of culturable microbes in the paddy soil contaminated with chemical pesticides were less than the actual diversity of species and cultivars, this study could help primarily indicate the adverse effects of the use of chemical pesticides. They thus interfered the ecological balance of the number and type of microorganisms especially at the site doing pesticide application.