Dissipation Kinetics of Penoxsulam in Soil of Rice Ecosystem

The persistence of penoxsulam applied in puddled rice fields at 20, 25 and 30 g a.i. ha⁻¹ for weed control is reported. The dissipation rate followed first order kinetics. In soil and water, it dissipated to below the limit of quantification (LOQ) of 0.01 μg g⁻¹ in 30 and 10 days respectively at 20 g a.i. ha⁻¹. However, at 25 and 30 g a.i. ha⁻¹, the residues dissipated to below LOQ in 45 and 21 days respectively. Half-life of penoxsulam in soil ranged from 6.40–7.88 days and in water from 3.40–5.12 days at the three doses. Residues in soil, rice grain and straw at harvest were below the maximum residue limit of 0.01 μg g⁻¹.