Conversion of surface irrigation system to overhead spray irrigation system

Department of the Environment, 2014

Ricegrowers' Association of Australia Inc

On-Farm Irrigation Efficiency Program Case Study

Constructing the overhead spray irrigation system

Location: Binya, New South Wales

Australian Government funding: $450,000 (GST Inclusive) Round: One

Project: Conversion of surface irrigation system to overhead spray irrigation system

Water transferred to Commonwealth: 250 ML

Project began: April 2011

Project completed: June 2012

Matt and Monica Molloy run 'Carrigane' a 2000 hectare property at Binya in the centre of the Riverina area of New South Wales. The Molloys were keen to improve their water efficiency and long-term farm sustainability by modernising their irrigation infrastructure.

The Molloys grow cotton and alternate between maize and soybeans annually. The Molloys received an On-Farm Irrigation Efficiency Program grant from the Australian Government to convert their existing irrigation system to overhead spray irrigation and recirculation system on 175 hectares of their property.

The original irrigation on the farm was an old style contour layout with many narrow irrigation bays and supply and drainage channels. The steep grade of the land made the area unsuitable for large-scale land-forming to create an irrigation layout of terraced bays and bankless channels. The Molloys decided a lateral move irrigator provided the best design option for their cropping area. The new irrigator and drainage system, which recirculates all tailwater back into the water supply system through a pumping station, gives the Molloys a highly productive and water efficient irrigation layout for their farm. The property is now in a much better position to maintain production using less water.

Constructing the overhead spray irrigation system

"We have saved at least 330 megalitres of water" the Molloys said.

As part of the project, the Molloys upgraded several pieces of machinery to increase the production efficiency and water savings on the farm.

"We upgraded the guidance system on the tractor so the drop-down spray units of the irrigator could be located between plant rows."

"We also converted the row crop equipment from six to eight rows to increase machinery efficiency and upgraded the seeder for better precision planting."The Molloys used their own funds to purchase a moisture monitoring system to add to the water use efficiency of the high-value crops. "These machinery upgrades plus the length of run provided by the lateral move irrigator has resulted in an estimated 20 per cent gain in machinery efficiency."

"The labour savings have also been huge, in-crop irrigation took 6-8 hours of labour with the original layout, it now only requires about 2 hours a day."

The project is also providing environmental benefits in terms of long-term soil health. The lateral move irrigator makes it easier to retain crop stubble, which can now be irrigated to help break it down. This increases soil carbon and the capacity to hold water in the soil improves soil health.

If not managed properly the clay soil on the farm is prone to a buildup of salinity and a hard surface. The new irrigation system helps reduce these problems.

The project's benefits have also extended to the broader community.

"Through this irrigation efficiency project, we've provided support for local businesses with extra engineering jobs and more earthworks with local contractors," the Molloys said.

On a personal level, the upgrade means the Molloys have more time for family.

"We live some 100 kilometres away from the farm, the new telephone-based monitoring system on the irrigator has saved considerable travel time to and from the farm, allowing more time for family and other recreational activities."

The water savings generated from on-farm projects are shared between the irrigator and the Australian Government. The government returns its portion of the water savings to the environment to protect and restore rivers, wetlands and other environmental assets in the Murray-Darling Basin. This will help 'bridge the gap' to the sustainable diversion limits under the Murray-Darling Basin Plan.

The 'gap' is the amount of water that needs to be returned to the rivers and wetlands of the Murray-Darling Basin to restore its health and underpin its industries. As a result of the infrastructure upgrades undertaken on the Molloys farm, 250 megalitres was transferred to the Australian Government for environmental watering, and will be used to benefit local assets such as Barren Box Swamp and the mid-Murrumbidgee wetlands.

More information about the program is available on the On-Farm Irrigation Efficiency Program web page or by calling 1800 218 478.