Soil Core Test, a Method of Pesticide Leaching Assessment for Upland Field

Abstract

A vertical infiltration of pesticides in upland field was evaluated by a soil core method. Surface soil layer (0-10 cm) was collected by a soil core collector (10 cm diameter, stainless steel) from an upland field treated with metalaxyl(Ridmil MZ®/wp), metolachlor (Dual®/EC) and bromacil(Hyper X®/wp). a steel cylinder loaded with vertically divided acrylic resin liner (5 cm inner diameter, 3 mm thickness) was guarded by stainless pipe (10 cm inner diameter, 10 cm height) and was driven to 50 cm under the surface. By this sampling method, the soil core from 10 cm to 50 cm layers was collected to be free from the contamination with pesticides in surface soil. The soil cores in acrylic resin liner collected from 6 spots in the field were divided in 10 cm soil layers, and mixed thoroughly for each layer. Soil water in each soil layer was separated by centrifugation at 11,000 rpm for 60 min at 4°C. The concentration of bromacil in soil water from 40-50 cm soil layer was 0.114 mg/L at 105 days after the pesticide application, while metalaxyl and metolachlor were not detected in soil water below 30 cm depth. No leaching water of pan-lysimeter was collected from the depth of 50 cm-soil layer. The leaching water in porous-cup laid at the depth of 50 cm did not contain any pesticide. © 2002, Pesticide Science Society of Japan. All rights reserved.