Information

Atrazine degradation and transport in runoff on a Black Vertosol – Felton Eastern Darling Downs

Level 1 General description

Purpose:

To better understand availability, dissipation, sorption, and runoff of atrazine, DEA, and DIA on the Darling Downs the fate of atrazine was monitored during the growth of a sorghum crop.

Methods (brief)

Two paddocks cropped with grain sorghum on a Black Vertosol were monitored for atrazine, potassium chloride (KCl) extractable atrazine, desethylatrazine (DEA), and desisopropylatrazine (DIA) at 4 soil depths (0–0.05, 0.05–0.10, 0.10–0.20, and 0.20–0.30 m) and in runoff water and runoff sediment.

Key findings (brief)

  • Only 0.5% of applied atrazine moved deeper than 0.20m into the soil, where it dissipated rapidly.
  • In runoff (including suspended sediment) atrazine concentrations were greatest during the first runoff event (57 days after application) (85 μg/L) and declined with time.
  • Even after 98% of the KCl-extractable atrazine had dissipated (and no longer provided weed control), runoff concentrations still exceeded the human health guideline value of 40 μg/L.

Location

A set of nested catchments south-east of Toowoomba on the Darling Downs, Queensland.

Related studies

Connolly and Rattray

 

Level 2, level 3, level 4 and level 5