Decomposition of herbicides in the soil by non‐biological chemical processes

Velocity constants of the decomposition reactions undergone by six herbicides when present in aqueous slurries of soils and clay were determined at 85°, 95° and 107°. It was assumed that biological action would not occur at these temperatures. Velocity constants at 20° were estimated by extrapolation. The results show that decomposition by purely chemical means is unlikely to be an important pathway of degradation for the herbicides studied, atrazine, chlorpropham, diuron, linuron, paraquat and picloram, as the half‐lives at 20° would be in the range 9 to 116 years.