Biobeds for Australian Agriculture; reducing the environmental impact of pesticide contamination

Overall Objective

The project will investigate and demonstrate the principles of biobeds for use on Australian farms with the aim of containing waste contaminated spray liquid. The project will design and build a biobed prototype to be used and tested on an Australian broadacre farm.

Workshops and demonstration days will be run to explain the concept, design and effectiveness of biobeds in an Australian farming environment. These workshops aim to increase participant knowledge associated with the environmental issues with current on farm practices relating to pesticide residue, creating more environmentally aware landholders and creating an option for practice change.

The project aims to find a solution to the current issues of disposing of chemical residue remaining in the spray tank after pesticide application which will lead to a reduction in soil and water contamination as a result of poorly disposed pesticide. There will be improved environmental outcomes.

Project Synopsis

Chemical application occurs as standard practice over the year on broadacre farms throughout Australia, and there will always be some residue remaining in the boom sprayer which will need to be rinsed out to avoid contamination from the following application. Commonly in agricultural enterprises, contaminated spray residue is disposed of after rinsing onto the ground and left to run off, causing contamination to soil and waterways, and thus potentially causing negative impacts to biodiversity and health of the environment. Biobeds have been widely researched and successfully implemented in European countries to manage this environmental issue.

This project investigated the system functionality of biobeds in a Western Australian climate for use on Australian farms with the aim of containing chemical rinsate. The process involved the design and construction of a prototype biobed located on a broadacre farm in the Northern Agricultural Region. The biobed prototype demonstrated the possibility of integrating such models into broadacre systems. All Biobed water sample results indicated an average reduction in chemical residue of 97%, demonstrating the benefits of disposing chemical residue in designated biobeds to reduce soil and water contamination.

The biobed prototype included 4 IBC’s (Intermediate Bulk Containers) with an organic biomix of compost/soil and mulch. Glyphosate was added at a concentration of 225 mg/kg to each IBC and water samples were taken at the completion of the project.

Residual glyphosate levels were as follows:

• Biobed 1 (inside) – 4.6 mg/kg or 97.95% reduction
• Biobed 2 (inside) – 4.2 mg/kg or 98.13% reduction
• Biobed 1 (outside) – 1.6 mg/kg or 99.28% reduction
• Biobed 2 (outside) – 10 mg/kg or 95.55% reduction

The results from the project indicated the use of biobeds is an extremely efficient method to reduce chemical residue when disposing of chemical rinsate. The prototype biobed system could be easily applied to broadacre systems and modified to suit the operations of growers considering logistics and locations may differ. Potential economic benefits to local farming communities would be increased income for local businesses from the required site works and purchasing of materials for installation of biobeds. A further economic benefit would be the reduction in risk from penalties surrounding environmental factors, for example contamination of water. By having a biobed system in place it would also reduce the effect of chemical resistance associated with current chemical rinsate systems which in turn will reduce the chemical cost and burden on growers.

The project faced some difficulties in the early stages of prototype design where it was preferential to have a large-scale concrete apron (able to be driven over with a spray rig) & associated biobed infrastructure installed at a property but due to some limitations the IBC size beds were developed. These were still successful prototypes in demonstrating the effectiveness of biobeds for reducing chemical residue and could easily be scaled out to be suitable for broadacre. A larger biobed system (farm scale demonstration) should be investigated to determine whether there are any other factors or different designs that could hinder the effectiveness of the biobed.