RRRD037 and RRRD038 Final Report

RRRD037 and RRRD038: Pesticide Dynamics in the Great Barrier Reef Catchment and Lagoon: Management Practices (Sugar, Grazing, Bananas) and Risk Assessments

Stephen Lewis and Jon Brodie

James Cook University, Townsville

pdfRRRD037-038_Research_Overview_Outcomes_Report_FINAL_Lewis-OVERVIEW.pdf968.93 KB

Executive Summary

Pesticide runoff from agricultural lands has been recognised as a serious threat to the health and productivity of the Great Barrier Reef (GBR) (e.g. Lewis et al., 2009) and is considered a priority pollutant for management in the GBR catchment area. Pesticide residues have been detected in marine waters, sediments, seagrass meadows and in freshwater plumes in the GBR lagoon. Water quality targets have been introduced to reduce the runoff of pesticides with the aim of improving ecosystem resilience in the GBR, although it was not known if the adoption of best management practices in agriculture will meet these immediate targets.

While it is clear that some pesticides have higher runoff potential than others due to their individual properties (i.e. persistence, solubility), a meticulous mass balance approach for individual pesticide chemicals was required to better parameterise/validate predictive models such as APSIM, HowLeaky? and Source Catchments to improve the accuracy of load calculations. This link is critical in the management of application rates of certain pesticides in the GBR catchments and to develop improved risk assessments for better management of the GBR. Moreover, the benefits of purported improved management practices to reduce the amount of pesticide runoff are largely unquantified. These links are critical in the management of application rates of certain pesticides in the GBR catchments and to inform/validate the modelling process within the RR monitoring and evaluation (M&E) program.

This project fostered collaborations between research scientists, growers and industry stakeholders to address the major unknowns of pesticide dynamics in the GBR catchment area. The project package incorporated a range of key science providers with expertise in the management, transport and fate of pesticides and the projects were conducted across several regions of the GBR catchment area. This package included a series seven sub-projects:

  • Determine the half lives in soils (and other key properties) of key pesticides used in the Great Barrier Reef catchment area for use directly in modelling for the Paddock to Reef Program
  • Investigate the potential water quality and agronomic benefits of alternative herbicide products (to those currently used) used in sugarcane including Balance, Flame, Soccer and Krismat
  • Determine the water quality benefits of improved practices to reduce pesticide runoff (Shielded sprayers, banded sprayers etc.)
  • Ascertain the half lives in water and the exposure of key pesticides in the Great Barrier Reef catchment area and lagoon
  • Tebuthiuron management in grazing lands
  • Partitioning of pesticides in agricultural lands
  • Pesticide management in bananas