EFFECT OF PESTICIDES ON INTERACTION AMONG CELLULOSE DECOMPOSITION, MICROFLORA AND SOIL-CONDITIONS - INSERTION OF CELLULOSE SHEETS IN FLOODED SOIL SAMPLES

Soil samples in which cellulose sheets were inserted were incubated at 30-degrees-C under flooded conditions. The fungicide trichlamide, (RS)-N-(1-butoxy-2,2,2-trichloroethyl) salicylamide, was applied to the soils as a representative pesticide with an inhibitory effect on the microflora related to cellulose decomposition. The cellulose decomposition, the changes in the populations of aerobic microorganisms in soil and the redox potential were monitored during the incubation. The microorganisms which colonized the cellulose sheets were observed microscopically. When the microflora was affected by the pesticide, cellulose decomposition was inhibited, colonization of the cellulose sheets by some microorganisms was not observed, and the development of the reductive conditions in the flooded soil was retarded. When the microflora on the cellulose sheets was not affected by the pesticide, no inhibitory effect on the cellulose decomposition was observed, and the reduction process was not appreciably retarded. These results suggested that the insertion of cellulose sheets in flooded soil samples combined with the microscopic observation of the cellulose sheets may afford a suitable model of the soil ecosystem to evaluate the effect of pesticides on the interaction among the cellulolytic activity, the microflora and the soil conditions represented by the redox potential.