EFFECT OF LINURON AND TRIFLURALIN USED IN SOYA CULTIVATION ON SOIL MICROORGANISMS

The effects of two herbicides, commonly used for chemical protection of soybean: Triflurotox 480 EC (trifluralin) and Afalonu 450 SC (linuron) on soil microorganisms were studied in a field and a laboratory experiment. Field experiment included three plots with three soyabean varieties Aldana, Augusta and Mazowia. One plot was amended with Triflurotox 480 EC, another one with Afalon 450 SC and the third one was a control plot without any herbicides. To characterize treatment effects on number of bacteria and fungi soil samples were collected in the vegetation period of plants (April-August 2007). To estimate the number of microorganisms, diluted soil was inoculated on the agar medium containing both herbicides (200 mg.dm(-3)). The study showed that bacteria and fungi responded differently to herbicides. The herbicides treatment had no effect on bacterial abundance as the number of bacteria in soil samples previously exposed to herbicides and in control soil samples was comparable. Fungi from the soil samples contaminated with Afalon 450 SE and Triflurotox 480 EC were more resistant to herbicides when exposed again to them in agar medium than fungi from control soil (without herbicides).