Microbiological and Physicochemical Properties of Carbamate Insecticides Treated Soil

Treatment of clay loam soil with carbaryl (sevin), thiodicarb (larvin) and methomyl (lannate) at field and 10 folds the recommended doses showed a variable effect on population of total bacteria, azotobacters and nitrifying bacteria, in addition to the soil content of total soluble salts; the effect differed according to the herbicide and the dose level. The bacterial population was significantly increased in the first five days of treatment, then a decrease was recorded. The increase in the microbial population and total soluble salts were proportion to the levels of the insecticides. Moreover, supplementation of glucose to the soil caused substantial increase over that in the insecticide and/or glucose free soils.