Dissipation of bispyribac sodium in aridisols: Impact of soil type, moisture and temperature

The study was conducted to evaluate the influence of physicochemical properties of soil, moisture and temperature on the dissipation behaviour of bispyribac sodium under laboratory conditions. Bispyribac sodium residues were extracted using matrix solid phase dispersion and were quantified using liquid chromatography tandem-mass spectrometry. The mean percent recovery of bispyribac sodium from studied soils ranged from 82.7 +/- 8.3-105.1 +/- 2.6%. The limit of quantification and limit of detection was 0.006 and 0.002 mu g g(-1), respectively. Dissipation of bispyribac sodium followed first order kinetics and soil type greatly influenced the dissipation behaviour of bispyribac sodium. Dissipation was faster in loam soil (DT50 = 12.79-14.52days) followed by clay loam (DT50 = 22.01-23.15days), sandy loam (DT50 = 23.34-25.17 days) and loamy sand soil (DT50 = 25.39-27.32days). The amendment of soil with FYM enhanced the dissipation of bispyribac sodium by 1.86-5.96-fold. It dissipated slowly under submerged (DT50 = 21.41-40.96days) conditions as compared to field capacity (DT50 = 12.79-27.32days) in studied soils. The degradation rate increased with the increase in temperature in studied soils and DT so ranged from 12.79 to 40.96, 7.36-36.96 and 4.09-31.61days at 30, 40 and 50 degrees C, respectively.