The Fundamental Studies on the Development of High Performance Soil

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Since soils being located normaly in outdoors they are directly exposed to the influence of environment, it is very difficult to control artificially the reaction of soil microorganisms. We have focused to facts that many important functions which human being has expected for soils come from chemical reaction, especially bio-chemical one and that these reactions are carried out by soil microorganisms In this study we have started experiments firstly to examine the microbial ecology from the aspect of soil chemistry and then to select factors controlling the ecology or survival of microorganisms. Having acquired these knowledges, we have developed experimental technologies to control to some extent the bio-chemical reaction in soil by the application of the microhabitat materials, for example, micro-porous ceramics as a habitat for a soil microorganism. Through these experiments, we have clarified that microorganisms were strongly influenced by chemical and moisture conditions, and then, a practical application as a preventive technique of nitrate leaching in upland soil was devised by only burying organic materilas with high carbon-nitrogen ratio in subsoil. On the other hand, a succeeful method to establish an inoculated bacterium in soil was developed. The bacterial strain used was Sphingomonas paucimobilis SS86, which has a unique ability to aerobically assimilate gamma-HCH.The bacterium has been known to disappear rapidly when simply inoculated into soils, whereas the gamma-HCH-assimilating S.paucimobilis indigenous to the soil where gamma-HCH has been annualyly applied survives and becomes established. However, strain SS86 was found to establish itself when introduced into a soil which had been exposed to gamma-HCH before bacterial inoculation, showing the same dynamics in the soil as shown by the indigenous gamma-HCH assimilating S.paucimobilis. Use of a selective substrate was suggested to be a new method effective for establishing inoculated bacteria in soi