In the field, it degrades to one half of its initial concentration in 1 to 6 months. Degradation rate depends on weather conditions and soil type. Hexazinone may persist longer in areas with more leaf litter and during cooler weather. Hexazinone is broken down primarily by soil microorganisms. Hexazinone may also be degraded by light exposure.
Carbon dioxide is a normal and harmless atmospheric component.
The liquid formulation disperses in water. Hexazinone is persistent and mobile in soils and therefore could contaminate ground-water. It is not likely to leach beyond the root zone, however. However, hexazinone degrades rapidly in natural waters. Hexazinone is not toxic to fungi, nitrifying bacteria, or other soil microorganisms at normal use rates.