Dissipation of Lambda-cyhalothrin under Organic Amendment in Vegetable Soils in Burkina Faso under Laboratory Conditions

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Résumé

Background and Objective: Pyrethroids are a group of pesticides widely used currently.Lambda-cyhalothrin is a pyrethroids insecticide used in Burkina Faso for crop protection.This insecticide efficacy is well known by vegetable farmers.However, no information is available on the persistence of lambda-cyhalothrin in soil under Burkina Faso climate conditions.The objective of this study was to determine the persistence of lambda-cyhalothrin in vegetable soil in Burkina Faso.Materials and Methods: The first experiment to determine the persistence of lambda-cyhalothrin was carried out under laboratory conditions in sterile and non-sterile soil to evaluate the microbial contribution to degradation.The second experiment has been done in soil with and without manure to evaluate the contribution of manure to lambda-cyhalothrin degradation.Results: During the incubation, 73.2% of lambda-cyhalothrin degraded in 7 days in nonsterile soil as opposed to 12.0% in sterile soil during the same period.During all the incubation period (20 days), lambda-cyhalothrin degradation was still slow in sterile soils (64%) compare to the degradation in non-sterile soil (83.7%).The half-life of lambda-cyhalothrin in sterile and non-sterile soil was 27.36 and 14.33 days, respectively.The results of the contribution of manure to lambda-cyhalothrin degradation have showed that the dissipation in soil in the presence of manure is higher (26.25%) than the dissipation without manure (21.5%) during the first 7 days and from 8-20 days after incubation.Conclusion: Microorganisms, abiotic factors and soil organic manure contribute to the dissipation of lambda-cyhalothrin in the soil.

Mots-clés

lambda-cyhalothrin, pyrethroid insecticides, pesticide dissipation, soil persistence, organic manure, microbial degradation, half-life, vegetable soil, abiotic degradation, sterile soil, Burkina Faso