Assessing Methods for Effects of Small Amounts of Chemicals such as Pesticides on Soil Ecosystem

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Previously we proposed recommended laboratory tests for assessing the side effects of pesticides on soil ecosystem. The method for 'nitrification activity' among the tests was evaluated by a 'ring test' between five laboratories. The protocol worked just about right but it was recognized that a few points such as pH arrangement of soil and incubation temperature should be considered.Quinone analysis was successfully used to assess the effect of Pentachlorophenol (PCP) and Bensulfronmethyl (BSM) on soil microbial community. The content of isoprenoid quinones is correlated with the microbial biomass, and most of microorganisms contain one major quinone does not change by the physiological conditions. Those results indicate that the difference in quinone composition directly reflects the difference in structure of microbial community in soil, and the analysis is a valuable method for the assessing pesticide effects on soil ecosystem.The Biolog method was examined as an isolation-independent method to characterize microbial flora in paddy soil treated with pesticides. Comparing the colored response pattern could assess the effect of pesticides on soil microbial flora.Denaturing gradient gel electrophoresis (DGGE) analysis of 16S rRNA amplified by PCR from soil DNA was evaluated for the assessing pesticide effects on soil microbes, especially on ammonium oxidizing bacteria. The amplification was confirmed but DGGE analysis was not completed. PCR-DGGE analysis for paddy soil microbial community elucidated a change in the community structure.Micro-thermo analysis was applied to the assessing pesticide effects on soil microbial activity but the sensitivity against chemical stress was not enough to detect it. Especially in paddy condition, thermo evolution was too small to measure with practical precision ; further examination for testing conditions such as substrate concentration should be needed.