Earthworm burrowing and feeding activity and the potential for atrazine transport by preferential flow

Soil columns with established earthworm burrow structures were subjected to 14 and 47 mm h(-1) rainstorms to study the effects of Lumbricus terrestris L. burrowing and feeding activity on preferential atrazine transport in so il. Earthworm treatments for the soil columns were as follows: earthworms i ntroduced 1 d prior to herbicide application, earthworms introduced 9 d aft er herbicide application and no earthworms added following herbicide applic ation. Rainfall was applied at 9, 18, 29, 40 and 51 d following [U-ring-C-1 4]atrazine applications onto crop residues at the soil surface. The concent ration of radioactivity in leachate was greatest during the first rainfall simulation and decreased in the subsequent four simulated rainfall simulati ons. Preferential herbicide transport through earthworm burrows was observe d during all rainfall simulations, but total atrazine and metabolites in le achate at the end of the five rainfall simulations were approximately 2-fol d greater in the absence than in the presence of earthworms. Earthworm feed ing activity reduced the potential for herbicide leaching by ingesting and transporting herbicide residues away from the soil surface and increasing t he amount of non-extractable (non-leachable) herbicide residues in the soil . Crown Copyright (C) 2000 Published by Elsevier Science Ltd. All rights re served.