Quantitative effects of some pesticides on certain physiological groups of micro-organisms in soil

Microbiological characteristics of a sandy loam soil exposed to tebuconazole and λ-cyhalothrin under laboratory conditions

“…However, the cfu counts increased in all treated soils compared to the control 2 weeks later ( Table 1). The decrease in numbers of the bacteria exposed to other fungicides has also been found (Makawi et al 1979;Martinez-Toledo et al 1998). When the soil was exposed to different concentrations of the insecticide, increased numbers of nitrogen-fixing bacteria were ascertained according to the level of contamination on all sampling times (Table 1).…”

“…Conversely, the higher the fungicide treatment of soil was, the higher cfu numbers of nitrifiers were determined on day 28. In other studies, the growth inhibition of nitrifying bacteria exposed to fungicides has been reported (Makawi et al 1979;Martinez-Toledo et al 1998). This group of bacteria was also sensitive to the highest concentration of the insecticide that was especially seen shortly after the soil treatment.…”

“…The effect was also noticeable on day 14 and, as not significant, on day 28 (Table 1). Considering examples of other insecticides, nitrifying bacteria have been more sensitive as indicated decreased cfu numbers (Makawi et al 1979;Martinez-Toledo et al 1993). Compared to nitrifiers, numbers of denitrifying bacteria was not affected by tebuconazole after its addition to the soil.…”