Persistence of bromacil in soils with different management histories

Two trials on a soil with no previous bromacil use showed that bromacil was degraded within 4 to 6 months when single applications were used, but persisted in the top 75 mm of soil for nearly a year when two applications were used in the same season.A third trial on a similar soil with a 10 year history of asparagus management and associated bromacil use showed increased chemical residue levels in lower depths of soil and slower degradation rates.Microbial biomass and activity in the first of these trials indicated that two bromacil applications caused considerable stress on the soil microflora, possibly contributing to the retarded bromacil degradation with repeated bromacil usage.