Rainfed crops hold the ground as irrigation dries up

by Kellie Penfold, GRDC

For farmers in the Murrumbidgee Irrigation Area (MIA), a plentiful water supply has for decades guaranteed harvests and allowed them to grow high-value rice crops.

But in recent years water allocations have dried up, mirroring the climate.

Many MIA farmers are turning to conventional dryland cropping, determined to learn the advanced moisture-retention systems practised by the best growers in other parts of the country – a knowledge they hope will benefit them even when the irrigation tap is turned on again.

Rainfed crops hold the ground as irrigation dries up Improving his winter cropping program is helping this irrigation farmer keep a cashflow while waiting …
and waiting, for the irrigation channels to flow again.

Rob Houghton stands in the GPS-precise lines of his well-emerged winter barley crop and declares that if a decent water allocation was announced in early spring he would happily spray out the barley to make way for rice. It’s a statement to make a dryland grain grower wince. However, rice remains king for Rob and his wife Jenny on their 530-hectare farm at Gogeldrie, near Leeton in southern NSW, despite it being dryland cropping that has paid the bills in successive low-water-allocation years.

Due to the lack of allocation, Rob hasn’t been able to reach the fine-tuned farming system he feels will be the most profitable for his country … irrigated rice and soybeans, followed by winter dryland cereals that utilise any residual moisture while aiding good weed control for the next irrigated summer crop.

“I’m just one farmer trying to make ends meet when we have no allocation,” Rob says. “I’m building a bridge until the good times return … although each year it seems the bridge is getting wider.”

Without irrigation, much of the farming land in the Murrumbidgee Irrigation Area (MIA) becomes marginal farming country. Rob estimates dryland crops return 10 to 25 per cent of what is achievable growing rice. And that is with some irrigation to finish the crops in the spring.

“I take my hat off to dryland farmers (because) adding water makes irrigation crop growing guaranteed. To grow dryland crops takes another level of management; a real farming ability.”

Rob recalls putting a proposal to the bank manager in 1989 with a program based on what he thought at the time was the absolute worst-case scenario – a 60 per cent allocation.

Last year, the Houghtons, along with other general security licence holders in the MIA, received 26 per cent of allocation. The year before it was 15 per cent.

With a general security licence of 3263 megalitres, the environmental limit for rice growing on the Houghtons’ land is 120ha. Last year they grew 32ha of rice and no other summer crop.

Rob’s strategy is that if allocations are announced in time for rice planting (October through to late November), he will plant according to water availability. The next option is soybeans, with a planting window closing in mid-December. If the announcement is made too late, he will carry the water over to the following year.

The juggle for irrigation farmers like Rob is that winter crops effectively become a weed if they subsequently receive an adequate water allocation. While watering the dryland crops could more than triple their yield, the economics remain dubious when grain prices are stacked against water that costs $300 a megalitre.

Nonetheless, who knows when irrigation supplies will return to ‘normal’ so Rob has set himself the challenge of improving dryland winter crop yields by introducing

guidance sowing techniques and lifting soil quality. While investigating how he
can best employ controlled-traffic farming (CTF) and precision agriculture (PA) systems to utilise winter moisture, Rob and some neighbours are looking at a plan for sharing large-scale farming equipment.

To make it worth owning broadacre equipment, Rob and his neighbours feel they need a critical mass of 2500ha of winter cereals between them.

It is also possible that private investors may become owners of the water licence or land, which would provide funds for farm improvements such as moving to a better paddock configuration to accommodate the irrigation of both summer and winter crops without changing the layout.

“We need to move away from this concept of ownership of everything – land, machinery and water. Access to water is vital, but ownership is probably a luxury in today’s climate.”

The ideal rotation, he says, would be rice followed by seed oats, or soybeans followed by two barley crops. Barley’s shorter growing season lends itself to double cropping more readily than wheat. Canola, faba beans or chickpeas would be considered as part of the rotation if water allocations were too low for soybeans.

This year Rob has planted GairdnerA barley, which he expects to yield about 2.5 tonnes a hectare. With irrigation this would double. If the barley doesn’t make malt it is sold to the nearby Rockdale Beef Feedlot. On the rice layout the barley was inter-row sown into canola stubble using GPS on 40-centimetre
rows at 35 kilograms a hectare of seed, with 40kg/ha of MAP fertiliser blended with 5kg/ ha of humates. On the raised beds it was direct-drilled inter-row into canola stubble as well.

“A lot of the time we plant dry and we never have any trouble starting the crop off, but we need to improve water holding to get a better finish.” he says.

Rob is also working on improving soil humus and the water-holding capacity of his soils by green manuring a ryegrass, lupins, oats and faba bean mix prior to sowing

soybeans and spreading compost made from animal manure and rice straw to increase soil humus. Livestock have been removed from the system to reduce soil compaction.

“The compost is more a long-term approach to soil improvement, which when applied at 3t/ha helped lift our water-use efficiency,” he says.

Original source of the article from GRDC groundcover magazine, reproduced with thanks.

Citation

Land & Water Australia. 2010. Rainfed crops hold the ground as irrigation dries up. [Online] (Updated February 6th, 2010)
Available at: http://lwa.gov.au/node/3732 [Accessed Thursday 11th of March 2010 05:21:56 AM ].