Watertable fall pushes efficiency innovations
GroundCover™ Issue: 97 | 16 Feb 2012
- By Sarah Cole
Five years ago irrigators Krysteen and Bradley McElroy realised they had a problem on their farm. The underground watertable at their South Australian property at Padthaway had dropped significantly. Over a two-year period, their water pumps went from putting out 500 kilolitres an hour to barely 160 kilolitres an hour.
The groundwater they use comes from an aquifer that they have used for irrigation for the past 40 years. To surface irrigate their seeds means gravity-dispersing the water over the soil. They also use the groundwater to drip irrigate a vineyard.
The south-east of South Australia is classed as a high-rainfall zone, but Krysteen says they have not seen big rains for almost 10 years. The McElroys have kept records of every irrigation event, pumping rate, rainfall and anything else that could affect their irrigation management.
This lack of rain meant the aquifer’s water levels were not topped up and the drop in pumping rate was how the McElroys discovered the falling watertable.
Switching irrigation systems
Their only solution, according to a study by the Natural Resources Management (NRM) Board with Price Merrett Consulting in Victoria, was to use what water they had more efficiently.
This meant upgrading their surface irrigation system to a surge irrigation system, which supplies water to the surface for short, planned time periods.
They also extended and compacted their channel holding areas (canals walled by soil). The channel extends into a paddock and has gates in its walls to control how water is let into the paddock. Each subsection of the paddock controlled by a gate is called a bay. Farmers open a gate, flood the bay with water and then close the gate.
These changes mean less water is used and plants are less waterlogged, resulting in a significant yield increase for their 2010 phalaris seed crop.
“We used to pump three megalitres of water into a channel and if the gate was open the water would go straight into a hectare-sized bay,” Krysteen says. “It was taking about 10 hours to water a bay, which was an inefficient use of diesel and power.”
With their new surge irrigation system, the McElroys fill up a channel and when it’s full, sensors automatically release one gate in the channel and water a bay with just over one megalitre. The gate shuts again, the channel fills up and the next bay is watered.
“It’s all very controlled and very efficiently done,” Krysteen says. She says the upgrading is turning out to be a huge success. “We have renewed enthusiasm for irrigation. We thought we were doing it OK before, but now we can see that we weren’t really. It’s exciting and motivating,” she says.
The next steps
The McElroys also carefully retain soil moisture, spraying to remove thick grass between crop rows to stop irrigation water from being held up and soaking too much into one area.
Soil moisture monitoring also allows the McElroys to water according to need. “Sometimes we need to water after six days, sometimes after 12. We used to just start the pumps after 10 days,” Krysteen says.
“Keeping accurate records throughout the irrigating season is one of the most important things we do,” Krysteen says. Tracking rainfall and irrigation gives them a baseline to monitor trends and results over years.
The McElroys are also working to retain more stubble each year to save moisture. “We need to look at different planting methods to do that. In 2006 we sowed using a DBS [deep blade system] and those crops really stood out.”
Recently, retaining stubble has been difficult because snails are a problem in south-east SA. Some farmers are burning their stubbles, which although not ideal helps get snails under control.
Krysteen and Bradley value seeing how other people manage their enterprises. “If you pick up one new way to manage frost, for example, it could be the one thing that makes a huge difference,” Krysteen says.
Guiding other farmers to water efficiency
Using her experience, Krysteen McElroy wants to create a guide on new and practical opportunities to increase productivity and sustainability from high-value crops and water-efficient irrigation systems.
Krysteen’s idea has earned her a place as a finalist in the 2012 Rural Industries Research and Development Corporation’s (RIRDC) Rural Women’s Award, which recognises and encourages rural women’s contribution to primary industries, resource development and rural Australia.
Growers in south-east South Australia use a wide variety of irrigation delivery systems: surface, drip, pivot, sprinklers, spraylines and more. This is why Krysteen believes investigating high-value crops that use irrigation efficiently will be extremely useful for her region.
People may ask ‘Why is the guide needed?’ or ‘Aren’t people already diversifying and growing higher-value crops?’ but Krysteen says it can be hard to know where to begin and who to contact. The guide would show what opportunities are available, how farmers can learn more, who to contact, and how to get the ball rolling.
Krysteen and Bradley don't use many formal climate forecasting tools in their decision-making, instead relying on their own soil moisture monitoring and websites for daily temperature and wind readings. Krysteen says they look forward to more reliable climate outlooks.
Growers: Krysteen and Bradley McElroy
Region: Padthaway, south-east South Australia
Commodity: Grapes, broadacre cropping (beans, wheat, canola), small-seed crops (lucerne, phalaris), livestock (sheep, lambs, cattle)
Farming area: 500 hectares
Annual rainfall: 400 to 550mm
The GRDC’s Climate Champions program provides early access to research assessing the impact of climate variability in different agricultural regions and helps growers adapt their production systems. Participants have been selected for their willingness to learn more about the influences of climate variability and to provide leadership to other farmers by sharing their experiences and what they have learnt.
IMAGE CAPTION: The McElroys have compacted the base of the channel and automated the gates for each bay (to the right). Photo: EConnect
IMAGE CAPTION: Bradley McElroy explains the surge irrigation system to Climate Champion farmers on tour in South Australia in October 2010. Photo: EConnect
IMAGE CAPTION: Krysteen McElroy has farmed at Padthaway for 20 years. Photo: EConnect
GRDC Research Code EC00003
GRDC Project Code EC00003
Region National, North, South, West
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