RRRD037 Progress update

November 2012

Science Summary:

Objective 1: Determine the half lives in soils (and other key properties) of key pesticides

-  A literature review on pesticide soil half lives in tropical environments and the parameters that affect them is now at a 3rd draft. The review includes published literature from tropical locations around the world, and the data from the Paddock to Reef Program.

-  The glasshouse trial, where the soil half-lives of 14 different herbicides have been measured on 8 different soil types from across the Great Barrier Reef catchment area has commenced and results should be available by early next year.

Objective 2: Investigate the potential water quality and agronomic benefits of alternative herbicide products

-  Preliminary data suggest that Balance and Flame have relatively short soil half lives and are not particularly persistent in the environment; however, final results/extra trials need to confirm this finding.

-  Reports have also been obtained from BSES on agronomic data of these alternative herbicides and growers and industry extension staff are being consulted to compile information on these alternative products.

Objective 3: Determine the water quality benefits of improved practices to reduce pesticide runoff.

-  A series of spot spraying rainfall simulation trials have been conducted in the Mackay Whitsunday and Burnett-Mary regions to demonstrate the water quality benefits (reduced runoff) of certain chemicals (gylphosate, 2,4-D, diuron, hexazinone, metolachlor). The results to date show that there are lower runoff losses of knockdown herbicides compared to residual herbicides. Both trials show the reduced amount of herbicide that is lost from a paddock where less amounts are applied (via spot spray). The Burdekin trial has also examined the field dissipation rates of a number of herbicides and results should be available shortly. This study is valuable to directly compare with the results obtained from the glasshouse trial.

Objective 4: Evaluate management options for minimising off-site movement of colloidal and dissolved-phase pesticides using flocculants such as polyacrylamide

-  This objective has been modified to boost the sampling undertaken as part of Objective 3.

Progress Update:

-  Activities and milestones are progressing well.

-  A preliminary glass house trial to obtain herbicide half life data on selected soils has been performed with the results from the laboratory forthcoming.

-  The key properties (and potential benefits) of alternative products are being examined at newly established trial sites at Silkwood and Ingham, and additional sites/trials are currently being considered. Data are now available from the alternative herbicide trials and data has also been collated from related work in this field and field dissipation rates have been calculated. Contacts have been sought to set up a working group to examine the pros and cons of the alternative herbicides that are available. Several of the alternative herbicides have been included in the recent Burdekin rainfall simulation trial which will provide valuable data on the potential runoff losses from the paddocks and field dissipation rates between the hill/mound and the furrow/row of the paddock.

-  Limited data now available on the best management practice trials but work on this to be boosted by the re-arrangement of the project to put more effort into this at the expense of sub-project 4 (see below) due to be conducted in November. Some results have been received from the laboratory on recent rainfall simulation trials examining spot spraying in the Mackay Whitsunday and Burdekin regions. These results appear to confirm the reduced runoff losses of pesticides from paddocks where spot spraying techniques are applied.