Effect of maize straw amendment on formation and translocation of residues of methabenzthiazuron in an orthic luvisol

Abstract

Abstract [Phenyl‐U‐14C]methabenzthiazuron (MBT) was applied preemer‐gence to winter wheat in November 1992 on two lysimeters (1 m2, 1.10 m depth) containing undisturbed soil monoliths of an orthic luvisol. One lysimeter was additionally amended with non‐labeled maize straw at a rate of 9 t/ha. In order to study the fate of the maize straw in soil a third lysimeter was amended with 14C‐labeled maize straw. Leachate was sampled every 2 weeks and analyzed for concentrations of 14C, MBT, and total organic carbon (TOC). Soil samples from the 0–25 cm of the plough layer were taken 255, 316, and 357 days after application of MBT and analyzed for concentrations of 14C, residues of MBT and its major metabolite demethyl‐methabenzthiazuron (A‐MBT), and 14C in bound residues. The average concentration of MBT in the leachates amounted to 0.02 ug MBT/L after amendment of maize straw and 0.05 ug MBT/L for the lysimeter without organic amendment. The amendment of maize straw enhanced the degradation of MBT and the format...