8 February 2017, 01:20PM
Cotton growers in Australia are changing the way they farm, after years in drought forced a rethink of water management practices.

Furrow irrigation has long been the hero of the cotton industry but now increasing numbers of growers are turning to overhead sprinkler irrigation to give them more flexibility over where and how to use their water allocations.

Tom Quigley, who with his parents and brothers runs “Muntham”, a mixed irrigation and dryland farming and livestock operation at Trangie, in Central West NSW, is among those who now grow cotton under an overhead sprinkler system.

The catalyst for Muntham to make the change was the significant government incentives to invest in more water-efficient farm infrastructure, in exchange for water entitlements under the 2007 Murray-Darling basin plan.

“We’d been through a long drought and hadn’t had a lot of water, so we wanted an ability to grow any crop into the future, with a wide range of water allocations,” says Tom.

But with cotton having been grown under furrow irrigation almost exclusively since the 1960s, they faced the question of would they be able to continue to grow cotton under their new Valley Central Pivot and Lateral Move irrigators. 

Tom applied for, and won, a $30,000 cotton-industry sponsored Nuffield Scholarship to research the possibilities. It took him to the USA, Canada, Mexico, Brazil, Israel, England and New Zealand over four months.

“The idea wasn’t to go and look at just cotton farms overseas, I wanted to meet farmers who have been growing crops under overhead sprinkler irrigation for a long period of time to accelerate our learning,” explains Tom.

Armed with his new knowledge, the family began experimenting on their own cotton crops and discovered they could obtain great yields using less water, but it needed a whole new way of thinking.

 “There’s a real stigma in the cotton industry that overhead irrigation machines can’t keep up with the demand of the cotton crop,” says Tom, “but the crux of it is you can’t grow it the same way as you grow a furrow irrigated cotton crop. You have to treat them as two entirely different crops.”

He found growing cotton on the flat as opposed to the traditional raised beds of furrow irrigation was important because it reduces run-off and waterlogging.

Ground cover, strip tilling and machine upkeep are some of the other key changes Tom identified as necessary.

He says ground cover, such as retained stubble or a cover crop will reduce evaporation, retain soil moisture and help wet the seedbed evenly during early germination - all crucial for high yields and water use efficiency. 

Cotton is a small and fussy crop to establish but the Quigley family has had success implementing strip tilling at 30cm strips one metre apart with a 70cm untilled section to keep the stubble yet still providing a fine seed bed for germination.

But Tom warns all these adaptions will be of little benefit if the machines are not regularly maintained.

Precision irrigation brings with it an ability to apply water exactly where it is wanted, only when it is needed, but the investment in the capital means it must be looked after if yields are not to be compromised by machine glitches at critical times in the season.

“It is no good having all the capacity to irrigate if the machine breaks down because then you have zero capacity to irrigate your crop and a significant investment losing yield potential daily,” says Tom.

While he doesn’t recommend cotton farmers switch their entire farm to overhead irrigation, Tom’s own experience has found it brings notable advantages.

Muntham has been able to improve its water use and noticed a 10 per cent increase in their yields. The property is now regularly achieving two bales per megalitre of water applied.

It also enabled them to use small amounts of water to grow opportunity crops when they needed to.

Applying less than a megalitre to the hectare, they were able to increase their chickpea yield by 1.5 tonnes per hectare providing a gross income of $1400 per MegaLitre compared to the $400 / ML they get for cotton.

“With overhead sprinkler irrigation you can spread not a lot of water a long way,” says Tom.

“With furrow it is all or nothing – you either saturate, or you don’t, whereas with an overhead sprinkler you can take a parcel of water and sprinkle it evenly over the entire area.”

The technology available with Valley irrigators means systems can be set up to enable variable rates of water to be applied over a field.

To find out more about Valley’s Central Pivots or Lateral Move Irrigators and how it can be made to work to your advantage, contact us on 02 6885 5220