Research: Improving irrigation in the Murray-Darling region of NSW

Eight hundred horticulturists in the lower Murray Darling region of NSW irrigate approximately 12 600 hectares. The region is dominated by grape vine and citrus growers. In the past the region has experienced salinity and waterlogging problems associated with rising groundwater due to seepage of excess irrigation water soaking deep down into the soil.

Farmers in the lower Murray Darling region of NSW have made massive savings in their water consumption thanks to infrastructure upgrades, education and uptake of Irrigation and Drainage Management Plans. These savings began ocurring from the mid to late 1990s, prior to the water supply drought which has become a significant issue in recent seasons and has required irrigators to become even more efficent, as well as rewarding those who had made earlier improvments to their efficency.

Upgrades to irrigation infrastructure, both on and off the farm resulted in 30% to 60% savings in three irrigation districts which divert water from the Murray and Darling Rivers onto irrigated farms. On the farm, surface irrigation methods which include flood and furrow irrigation, have more than halved and drip irrigation had tripled.

The gains in infrastructure include the upgrade to a pressurised or semi-pressurised pipeline system in all major irrigation districts within the Murray Darling region. This has reduced the amount of water lost through distribution channel seepage (water soaking into the soil), evaporation and from water escaping from the concrete or earthen channels.

NSW Department of Primary Industries Irrigation Officer Jeremy Giddings says that "over 80% of the irrigation community have now completed formal irrigation training and the information gained has become standard knowledge throughout the irrigation community".

"This education program has stimulated the adoption of Irrigation and Drainage Management Plans (IDMPs) and irrigation scheduling using the more sophisticated scheduling tools", he said.

Irrigation and Drainage Management Plans help farmers to understand how much water they use, and how they can maximise every drop of water for productivity gains. Some of the questions farmers answer in their plans include how much water their crop rootzones hold? How quickly do the crops use water from the rootzone? How long does it take to irrigate to refill the rootzone? And how quickly does irrigation get into the rootzone?

Scheduling is the process of understanding the farms soil characteristics so that soil moisture is kept within a desired range for healthy crops, efficient use of water, reducing drainage and optimising crop yields and quality.

The upgrades to the water supply system in the Murray-Darling region have meant that farmers have a reliable, flexible and frequent water supply, and the ability to adopt more efficient irrigation systems. Poor water supply in the past had a significant effect on the adoption of drip irrigation. Drip irrigation for example requires smaller amounts of water applied more frequently.

"These improvements have resulted in significant benefits to the local community and the environment. Metered drainage outfalls have fallen by 85% since 1998 and average groundwater heights by 2 m in some areas", he said.

Source: Giddings J, 5th International Symposium of Irrig. Hort. Crops 28 August 1 September, Poster presentation 'Improving Irrigation Efficiency in the Lower Murray-Darling Region of Australia', 2006.

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