New trials by the CSIRO have minimised herbicide runoffs from farming operations that threaten Australia’s iconic World Heritage listed Great Barrier Reef.
In the trial the CSIRO’s Water for a Healthy Country Flagship trialed a new specially adapted shielded sprayer for applying herbicides to a raised bed of furrow irrigated sugar cane.
The new sprayer minimises the likelihood of herbicides coming into contact with irrigation water.
Many herbicides used in the lower Burdekin region of northern Australia are PSII herbicides that are known to negatively impact reef ecosystems.
Improved farming techniques such as the shielded sprayer, help keep herbicides on-farm and improve the water quality on the Great Barrier Reef.
“The conventional application of herbicides in furrow-irrigated sugarcane production is to broadcast spray across the whole field using boom sprayers, which applies herbicides to both beds and furrows. Irrigation water then carries the herbicides with the tail water into the drainage channels, into nearby creeks and rivers and potentially into the GBR lagoon,” CSIRO research leader, Dr Rai Kookana said.
“Given the importance of improving GBR water quality additional testing and demonstration of these technologies across different soil types, farming systems – and possibly with different combinations of chemicals – would provide valuable additional testing of the approach from an industry perspective.
“These trial results are extremely encouraging, and clearly demonstrate that the use of precision herbicide application technologies by the industry, including using shielded sprayers for furrow-irrigated sugarcane cultivation, can be highly effective in reducing herbicide run-off.”
According to Jon Brodie, Principal Research Scientist from the Centre for Tropical Water & Aquatic Ecosystem Research of James Cook University, the concentration of some herbicides in creek and estuarine waters during the dry season regularly exceeds Australian water quality guidelines and could potentially affect coastal sea-grass.
CSIRO scientist Danni Oliver 
stated that “The trials show that while there will certainly be some herbicide loss following the first irrigation or rainfall event, the marked decreases in losses documented in this study—a reduction of to 90 per cent—could lead to significant improvements in off-site water quality, particularly during the dry season.”
The results of the study have been published in the international journal Science of the Total Environment.
