Microbe—Chloroacetanilide Herbicide Interaction across Soil Type

Abstract

An investigation was carried out under laboratory conditions to study the persistence of butachlor applied at recommended dose (2 kg ai/ha) along with its impact on microbial activity as well as growth of colonial bacteria and fungi in alluvial (Typic Haplaquent), lateritic (Typic Haplustalf) and coastal (Typic Haplaquept) soils. Butachlor caused a significant increment in microbial activity following an initial diminution in between 10 to 22 days of incubation depending on the type of soil. The herbicide resulted in a significant shrinkage in bacterial community during later stages of incubation in lateritic and coastal soils in spite of a significant swelling on the 15th day in lateritic and alluvial soils. Fungal community significantly expanded at the initial stage in lateritic soil and during later stages in alluvial soil by the application of butachlor but shriveled during later stages in the lateritic soil, intermediate stage in coastal soil and initial stages in alluvial soil. Alluvial soil reared the highest population of colonial bacteria and exhibited highest microbial activity while coastal soil significantly pressed them down to the lowest. However, lateritic soil was the best niche for fungal community. Co-metabolism was the main phenomenon in butachlor metabolism particularly in coastal soil, though zymogenous microbes including bacteria and fungi also participated in both lateritic and alluvial soil at certain stages. The persistence of butachlor was the lowest in alluvial soil followed by lateritic and coastal soil, respectively. Among the soil types application of butachlor is safe in alluvial soil.