Persistence of metsulfuron‐methyl in two soils

Abstract

The persistence of metsulfuron‐methyl in sandy loam and clay soil incubated at different temperatures and moistures contents was investigated under laboratory conditions using longbean (Vigna sesquipedalis L.) as bioassay species. A significant degradation of metsulfuron‐methyl was observed in non‐autoclaved soil rather than the autoclaved soil sample. At higher temperature, the degradation rate in non‐autoclaved soil improved with increasing soil moisture content. In non‐autoclaved sandy loam and clay soil, the half‐life was reduced from 9.0 to 5.7 and from 11.2 to 4.6 days, respectively when moisture level of sandy loam increased from 20 to 80% field capacity at 35°C. In the autoclaved soil, herbicide residue seems to have been broken down by non‐biological process. The rate of dissipation was slightly increased after the second application of the herbicide to non‐autoclaved soils but not in autoclaved soil, indicating the importance of microorganisms in the breakdown process.