title: Effect of fly ash amendment on metolachlor and atrazine degradation and microbial activity in two soils.
abstract: The study reports the effect of Inderprastha (IP) and Badarpur (BP) fly ashes on degradation of metolachlor and atrazine in Inceptisol and Alfisol soils. Metolachlor dissipated at faster rate in Alfisol (t1/2 8.2-8.6 days) than in Inceptisol (t1/2 13.2-14.3 days). The fly ashes enhanced the persistence of metolachlor in both the soils; however, the extent of effect was more in Inceptisol (t1/2 16.6-33.8 days) than Alfisol (t1/2 8.4-12 days) and effect increased with fly ash dose. 2-Ethyl-6-methylacetanilide was detected as the only metabolite of metolachlor. Atrazine was more persistent in flooded soils (t1/2 10.8-20.3 days) than nonflooded soils (t1/2 3.7-12.6 days) and fly ash increased its persistence, but effect was more pronounced in the flooded Inceptisol (t1/2 23.7-31 days) and nonflooded Alfisol (t1/2 6.3-10.1 days). Increased herbicide sorption in the fly ash-amended soils might have contributed to the increased pesticide persistence. The IP fly ash inhibited microbial biomass carbon at 5 % amendment levels in both the soils, while BP fly ash slightly increased microbial biomass carbon (MBC) content. Dehydrogenase activity was inhibited by both fly ashes in both the soils with maximum inhibition observed in the IP fly ash-amended Alfisol. No significant effect of fly ash amendment was observed on the fluorescein diacetate activity.
authors.affiliation: Division of Agricultural Chemicals, Indian Agricultural Research Institute, New Delhi, 110 012, India.|National Institute of Research on Jute and Allied Fibre Technology, Kolkata, West Bengal, India.
authors.forename: Rakesh Kumar
authors.initials: RK
authors.lastname: Ghosh
authors.affiliation: Division of Agricultural Chemicals, Indian Agricultural Research Institute, New Delhi, 110 012, India. drneerasingh@yahoo.com.
authors.forename: Neera
authors.initials: N
authors.lastname: Singh
authors.affiliation: Division of Agricultural Chemicals, Indian Agricultural Research Institute, New Delhi, 110 012, India.
authors.forename: Shashi Bala
authors.initials: SB
authors.lastname: Singh
mesh_terms: D000081:Acetamides / Q000032:analysis*; D001280:Atrazine / Q000032:analysis*; D001673:Biodegradation, Environmental; D018533:Biomass; D060729:Coal Ash; D004784:Environmental Monitoring / Q000379:methods*; D006540:Herbicides / Q000032:analysis*; D007194:India; D012987:Soil / Q000737:chemistry / Q000592:standards; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000032:analysis*
chemical_list: D000081:Acetamides; D060729:Coal Ash; D006540:Herbicides; D012987:Soil; D012989:Soil Pollutants; D001280:Atrazine; C051786:metolachlor
keywords: Atrazine; Degradation; Dehydrogenase; Fluorescein diacetate; Fly ash; Metolachlor; Microbial biomass