EFFECT OF PESTICIDE APPLICATIONS ON SOIL BIOMASS AND MICROBIAL RESPIRATION

ABSTRACT

The effects of pesticides on soil microflora were studied in soils that received the pesticide treatments recommended for cotton crops. Assessment of soil biomass and microbial respiration were done by the substrate-induced respiration (SIR) and the selective inhibition (SI) techniques. Pesticides both inhibitted or stimulated the increase of microbial biomass, depending on the soil type. Bacterial population was lowered by the pesticides, but its respiration prevailed on the fungi respiration. Variation on the respiration rates also occurred in the different seasons, independently of the pesticide applications. However, results indicated that the pesticide effects were only temporary.

KEY WORDS:
Bioactivity; substrate-induced respiration; selective inhibitors; pesticides.