International Journal of Plant & Soil Science

This laboratory study examined the persistence and dissipation of tricyclazole and tebuconazole in riverine alluvium soil under two moisture regimes: field capacity and submergence. Each fungicide was introduced separately at 1, 2 and 4 mg kg⁻¹, and soil samples were collected at intervals from day 0 to day 75. Residues were extracted using a modified QuEChERS procedure and quantified by liquid chromatography–tandem mass spectrometry. Method validation showed recoveries of 90.04–94.76% for tricyclazole and 80.04–92.09% for tebuconazole, with relative standard deviations below 5%. The dissipation of both fungicides was generally described using first-order kinetics. Mean half-lives across the evaluated treatments were 12.85 days for tricyclazole and 9.86 days for tebuconazole. Mean half-lives under field-capacity and submerged conditions were 13.52 and 9.19 days, respectively, indicating lower persistence under submergence. For tricyclazole, treatment-specific half-lives ranged from 6.61 days under submerged conditions at 1 mg kg⁻¹ to 18.95 days under field capacity at 4 mg kg⁻¹. Tebuconazole also exhibited shorter half-lives under submerged conditions than under field capacity at corresponding concentrations. Persistence generally increased with the initial fungicide concentration, particularly for tricyclazole. These findings indicate that fungicide identity, moisture regime and initial concentration influence residue dissipation in the soil examined. The results provide laboratory-based evidence for assessing the behaviour of these fungicides under contrasting moisture conditions relevant to paddy soils.