Environmental Fate of Fluopyram in Indian Soils: Persistence, Dissipation Kinetics, and Leaching Potential.

Abstract

The environmental fate of fluopyram was evaluated through laboratory dissipation, field dissipation, and soil column leaching studies using representative Indian soils. In vitro dissipation of technical-grade fluopyram (5 mg/kg) was investigated in six soils under aerobic conditions. Fluopyram dissipated slowly, with ~27-33% dissipation of the initial amount after 120 days of incubation. Dissipation followed biphasic kinetics best described by combined first-order and double first-order in parallel (DFOP) models, with estimated DFOP slow-phase half-lives ranging from 363 to 676 days. Under field conditions in sandy loam soil, fluopyram dissipated more rapidly, with ~60-75% dissipation within 90 days following application of 34.48% SC fluopyram at 0.5, 1, and 2 kg a.i./ha. Dissipation again followed biphasic, concentration-dependent kinetics, with DFOP slow-phase half-lives of 54, 130, and 252 days for the respective doses. Soil column studies showed soil-dependent mobility after simulated rainfall (~600 mm), with cumulative leaching of 56.5-64.4% in clay loam soil but negligible movement in clay soil. Based on relative mobility factors, fluopyram was classified as slightly to moderately mobile, indicating persistence combined with variable leaching potential in different soils. Overall, fluopyram exhibited high persistence and moderate mobility, indicating potential long-term soil exposure and possible subsurface transport under favourable conditions.