title: Soil persistence of triasulfuron herbicide as affected by biotic and abiotic factors.
abstract: Persistence of triasulfuron [3-(6-methoxy-4methyl-1,3,5-triazin-2-yl)-1-{2-(2-chloroethoxy)-phenylsulfonyl}-urea] in soil was studied under wheat crop and laboratory conditions. Field experiment was conducted in the farms of Agronomy Division, Indian Agricultural Research Institute (IARI), New Delhi. Randomized block design (RBD) was followed with four replicates and two rates of treatments along with control and weedy check. Triasulfuron was applied as post-emergent application to wheat crop at two rates of application viz., 15 g and 20 g a.i. ha-1. Soil samples at 0 (3 h), 1, 3, 5, 7, 10, 15, 20, and 30-day intervals after application were drawn, extracted, cleaned up, and analyzed for herbicide residues by high performance liquid chromatography (HPLC) using C18 column and methanol: water (8:2) as mobile phase at 242 nm wave length. Effect of microbial activity and soil pH was studied under laboratory conditions. Dissipation of triasulfuron followed a first-order-rate kinetics. Residues dissipated from field soil with half-life of 5.8 and 5.9 days at two rates of application. The study indicated biphasic degradation with faster rate initially (t1/2 = 3.7 days), followed by a slower dissipation rate at the end (t1/2 = 9.4 days). Similar trend was observed with non-sterile soil in laboratory with a longer half-life. Acidic pH and microbial activity contributed toward the degradation of triasulfuron in soil.
authors.affiliation: Division of Agricultural Chemicals, IARI, New Delhi, India. sbs_agch@yahoo.com
authors.forename: Shashi B
authors.initials: SB
authors.lastname: Singh
authors.forename: Gita
authors.initials: G
authors.lastname: Kulshrestha
mesh_terms: D001673:Biodegradation, Environmental; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004305:Dose-Response Relationship, Drug; D006207:Half-Life; D006540:Herbicides / Q000032:analysis* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D010573:Pesticide Residues / Q000032:analysis; D011897:Random Allocation; D012987:Soil / Q000032:analysis; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000032:analysis* / Q000378:metabolism; D013453:Sulfonylurea Compounds / Q000032:analysis* / Q000378:metabolism; D014908:Triticum / Q000737:chemistry*; D000096926:Benzenesulfonamides
chemical_list: D006540:Herbicides; D010573:Pesticide Residues; D012987:Soil; D012989:Soil Pollutants; D013453:Sulfonylurea Compounds; C094039:triasulfuron; D000096926:Benzenesulfonamides