Toxic effects of four sulphonylureas herbicides on soil microbial biomass

Abstract

The effect of four triazinyl-sulfonylurea herbicides (cinosulfuron, prosulfuron, thifensulfuron methyl, triasulfuron) on soil microbial biomass, soil respiration, metabolic activity, metabolic quotient, and some enzymatic activities (acid and alkaline phosphatase, β-glucosidase, arylsulphatase, and fluorescein diacetate hydrolysis) were monitored under controlled conditions over 30 days. The herbicides were applied at the normal field dose (FD) and at ten-fold (10 FD) the field dose, in order to mimic a long term toxic effect. The measured soil microbial parameters showed that the FD had slight effects on soil microflora, while at 10 FD the tested herbicides exerted a stronger detrimental effect on soil microbial biomass and its biochemical activities.

Keywords:

• Herbicides
• triazinyl-sulfonylurea
• respiration
• microbial biomass
• metabolic quotient
• soil enzymes.

Acknowledgments

This work was supported by a grant provided by the University of Basilicata, Potenza, Italy. The authors are grateful to Mr. L. Pariti for the technical assistance.