Irrigators look for economy and efficiency in water delivery

The new irrigation technical lead at CottonInfo is Lou Gall, who is also the Gwydir Valley Irrigators Association's externally funded project officer.

Ms Gall's role is to manage and report on all projects run by the GVIA while continuing to source additional funding from government organisations.

She attended the recent Irricom 2024, CottonInfo's third irrigation forum, which explored the water use efficiency of siphon-less and bankless designs.

"The importance and the need to investigate these methods have started to increase as we start by looking at how we do what we do better," Ms Gall said.

She said with the resources producers have to manage, water because it's potentially the most limiting resource.

"But we're also then faced with the challenges of a limited labour source as well.

"Most irrigators are working as hard as they can to secure the employment of their permanent staff and rely less heavily on transient staff, such as backpackers, because they have experienced this firsthand when backpackers aren't quite as readily available.

"Growers have been talking about this a lot and how we can do it better, and a number of different designers have been looking at different designs where we can remove the siphon.

Ms Gall said there were many different designs to consider and proposed they be divided into two basic categories: the siphonless design and the bankless channel design.

"There are limitations as to what design might fit your particular field and your farm. So what we tried to make sure we did is put together experiences in Irricom from different growers, what they've done, why they've done and how they've done it," she said.

"I think irrigators should first consider whether they are getting the most out of the system they're currently using.

"Have you really optimized the way you're using that in case you do what you're doing better?

"If you don't have enough staff to start your siphons the way they need to be started, you are limited, which is why so many growers are looking at alternatives.

"You also need to consider how much soil you are willing to move in changing your system.

"What sort of soil types do you have? If you have soil with very slow infiltration rates, that will inform the decisions you might be able to make.

"Most of the time, growers will want to try to minimize the amount of topsoil they move so that it's less expensive to put in and also better for the crop that gets planted after that.

"There are many cost considerations in there because you can imagine changing your design with fuel costs going up to run your scrapers."

Ms Gall said the Irricom event drew growers from Griffith, Warren, the Namoi, Gwydir, and McIntyre Valleys, and St George in Queensland.

"We had a number of growers who are looking at different designs and doing things differently so that we could get a really good cross-section of conversation," she said.

"To get the water to flow as uniformly across your bays is critical. The more uniformly you can get your water on and off at the time frames to where you saw profile down to the root zone for more efficient irrigation is going to be."

Ms Gall said another option worth consideration could an overhead or a drip system.

"It's really important for them to understand what they need to do to improve their business and water use efficiency."