Leaching Behavior of Oxyfluorfen 23.5% EC at Different Rain Falling Rates and Different Applications Rates

Abstract

Leaching is one of the key parameter for the contamination of ground-level water. A study was conducted to determine the leaching potential of oxyfluorfen following the Organization for Economic Co-operation and delopment (OECD) 312 guideline. The loamy sand soil collected from the IIBAT, padappai research farm was used. The collected soil was filled into the polyvinyl chloride (PVC) column (35 cm in length and internal diameter 4 cm) up to the 30 cm mark. The Oxyfluorfen 23.5% Emulsifiable concentrate (EC) formulation was sprayed @: 100 gram active ingredient/ hectare (g a.i/ha), 150g a.i/ha and 200g a.i/ha. The aim was to explore the impact of of artificial rain (0.01Molar(M) Cacl2) fall rates (60 millimeters (mm), 100 mm and 140 mm) on the leaching potential of the herbicide in soil. Before initiation of the study, the soil was characterized for soil type, the content of clay, silt, sand, organic carbon content, pH, dry weight, WHC max (maximum water holding capacity), and electrical conductivity. The column leachate was collected from the initial day up to 15 days and analyzed validated High-performance liquid chromatography using the diode array detector (HPLC-DAD) method. After completion of the experiment, the soil samples were extracted and analyzed by HPLC-DAD. The linearity concentration ranged between 0.005 – 10.0 mg/L of oxyfluorfen with a correlation coefficient of 0.9999 was established. The assay accuracy showed 90 – 92% recovery in 0.01M CaCl2 at 0.01 milligram/Liter (mg/L) fortification level; 92-94% at 0.1 mg/L fortification level and 95 -96% at 0.5 mg/L fortification level. Recovery in soil was 89 – 91% at 0.01 milligram/kilogram (mg/kg) fortification level; 92-94% at 0.1 mg/kg fortification level and 94 -96% at 0.5 mg/kg fortification level. The collected leachate residues at the rainfall rate 60 mm, 100 mm and 140 mm rainfall was 5.09, 10.93, 13.62 mg/L; 4.92, 9.33, 11.74 mg/L; and 5.22, 8.45, 9.56 mg/L at different dose rates 100g a.i/ha. 150g a.i/ha and 200g a.i/ha respectively.