Successful second harvest as part of Gloucester irrigation trial

AGL’s irrigation trial in New South Wales is showing continued signs of success, with a second harvest completed.

The trial, which began in March this year, produces water from deep in coal seams, which is blended with fresh water and used to irrigate crops at Gloucester. The process initially produces forage triticale – a common cereal crop – and lucerne, allowing AGL to test both perennial and annual crops.

Produced water is the term used to describe groundwater produced when coal seam gas is extracted from deep coal seams.

The irrigation trial is being conducted at AGLs Tiedeman site as part of the exploration phase of the Gloucester Gas Project. Crops are currently thriving since seeding in April, 2013.

Project overseer Andrew Leneham said the results are encouraging.

“There’s been good pasture growth in the field and the first harvest produced a great crop yield,” he said.

“We’ve already received requests from the community to purchase all of the bales from this harvest. There’s high demand because it’s seen as a high-quality product.”

AGL manager hydrogeology John Ross said the company wants to assess if, when blended with fresh water, produced water can be re-used for agriculture in a way that is safe and environmentally sustainable.

“If successful, this means that the community will have access to water for farming that would otherwise be unavailable, and means more fresh water for other community uses. At the same time it will produce additional fodder for livestock,” he said.

“Water from coal seams typically is treated and used for other purposes like brick-making. In undertaking this trial, we hope to uncover another sustainable use for it.”

Located approximately 15km south of Gloucester, the trial integrates with existing agriculture, grazing and gas operations.

The irrigator operates across 16 individual trial plots – about 12ha in total area – and will cultivate salt-tolerant crops in the next 18 months to two years. Produced water is blended at a ratio of 3:1 with fresh water, which substantially reduces the salinity.

The trial has been approved by the
New South Wales Department of Trade and Investment, Division of Resources and Energy, the New South Wales Office of Water, and the Environment Protection Authority.

Soil and water monitoring systems are in place to monitor the effectiveness of the trial. For example, to assess background conditions and the impact of irrigating with blended fresh and produced water, a soil and water monitoring network has been established.

Baseline monitoring was carried out for the 12 months leading up to the start of the trial and more intensive monitoring has been underway since the trial commenced in early April.

Utilising advanced technology, including a built-in GPS, soil moisture probes and controlled application rates, the linear move irrigator is a highly efficient method of irrigation.

With a maximum sweep length of 1036m, the irrigator conserves water by applying only the amount of water that is needed, where it is needed to optimise crop growth and to minimise runoff.