Effect of pesticides on cellulose degradation in soil under upland and flooded conditions

Abstract

The effect of pesticides on cellulose degradation in a soil was estimated by incubation experiments under upland conditions, transitional flooded conditions from aerobic to anaerobic, and fully anaerobic flooded conditions. Pesticides examined were trichlamide [(RS)-N-(1-butoxy-2,2,2-trichIoroethyl)salicyl-amide], chlorothalonil (TPN, 2,4,5,6-tetrachloro-1,3-isophthalonitrile), quin-tozene (PCNB, pentachloronitrobenzene), and hymexazol (3-hydroxy-5-meth-ylisoxazol) as fungicides, paraquat (1,1′-dimethyl-4,4′-bipyridium dichloride), thiobencarb (benthiocarb, S-p-chlorobenzyldiethyl thiocarbamate), propanil (DCPA, 3′,4′-dichloropropionanilide), and butachlor [2-chloro-2′,6′-diethyI-N-(butoxymethyl)acetoanilide] as herbicides, and diazinon (2-isopropyl-4-niethyl-pyrimidyl-6-diethylthiophosphate) as insecticide. Trichlamide inhibited completely the cellulose degradation under the two flooded conditions, while the inhibition under upland conditions was weak. The inhibition by chlorothalonil was strong under all conditions, while quintozene and hymexazol did not display any inhibitory effect. There was a difference in the effect of fungicides between upland and flooded conditions, but not between the two flooded conditions. The inhibitory effect of the herbicides and insecticide was not observed under upland and transitional flooded conditions.