Persistence of simazine and hexazinone in soil

A study on simazine and hexazinone persistence in soil was performed under field and laboratory conditions. The laboratory assay showed an increase of the degradation rate of both herbicides with soil temperature and moisture content. The effect of temperature was higher for simazine, while soil moi sture content had a higher influence on hexazinone degradation rate. In the experiment under field conditions, the half-life obtained for simazine was near 44 days and that of hexazinone was about 35 days. These field persist ence data agree with those predicted by a simulation model using the degrad ation rates obtained under laboratory conditions.