Effect of agrotoxics in biological activity of two soils in laboratory experiments.

Abstract

The influence of the fungicide pentachloronitrobenzene (PCNB), the herbicide trilluralin and the  fungicide metalaxyl-mancozeb on the biological activity of the Red Yellow Podzol and Red Latosol soils, under  laboratory conditions, was measured by radiorespirometry. Metalaxyl-mancozeb was inhibitory to the microbial  activity, in the concentration of 1 mg and 10 mg/g of soil. This inhibitor effect persisted even when metalaxyl-  mancozeb was added with trifluralin and PCNB, that had low influence on microorganisms when used  individually. The pesticide effect changed according to the soil type, being higher in the Red Latosol soil, with  the higher clay content. Effects on the biological activity was also influenced acoording to the different pesticides'  concentation in a combined mixture applied to the soils.