Research puts canola in the mix

MIXED farmers keen to supercharge business returns will find plenty of interest in dual-purpose canola.

CSIRO researchers have estimated the value of incorporating dual-purpose canola into Australian mixed farming systems at more than $1 billion in the past 15 years.

While growers may already be familiar with the gains possible from dual-purpose canola, reviewing how the crop was developed – and its advantages to farming systems – is a valuable exercise, particularly for those new to the cropping industry or seasoned growers looking to generate higher returns.

CSIRO agriculture and food chief research scientist Dr John Kirkegaard planted his first dual-purpose canola trials in 2004 to explore the impact of grazing on grain production.

“In the high-rainfall areas, dual-purpose cereals were profitable, but growers with grass-dominant pastures had no break crop option and were running into problems with weeds and diseases,” Dr Kirkegaard said.

Accordingly, he and his CSIRO colleagues were determined to explore how well canola recovered when grazed at various stocking rates and the effects on grain yields.

Those proof-of-concept trials compared ungrazed canola with canola grazed at both light and heavy stocking rates. They also compared the palatability of canola with European forage brassicas.

“To our surprise, the first grazed canola crops grew back well with minimal effect on a final grain yield of about three tonnes per hectare,” Dr Kirkegaard said.

“We were excited by the results, so in 2005 we invited growers and advisers to see the grazed canola immediately after we had removed the sheep and later when the crops had recovered.

“Those who visited our trials … were enthusiastic about the idea of dual-purpose canola and became involved in our early research.”

Accordingly, in 2007, they implemented the first on-farm test of a European canola variety. This was planted at Bobbara Station, near Galong in southern New South Wales.

Dr Kirkegaard said one of the first tasks in developing dual-purpose canola was to ensure blackleg disease could be managed.

“Blackleg spreads when aerial spores – released during autumn and winter – enter plants through small openings known as the stomata in leaves,” he said.

“Back then, we thought that sheep grazing canola would increase the blackleg risk.

“Dr Susie Sprague did most of the work in those early years to ensure growers could manage the disease. Her research demonstrated that planting canola varieties highly resistant to blackleg would limit the incidence of disease resulting from grazing.

“She also showed that removing grazing animals before stem elongation limited the incidence of blackleg infection.”

At the same time, the late CSIRO researcher Dr Hugh Dove and his assistant Scott McDonald were exploring the palatability of canola, the growth rates of sheep grazing canola and whether there were any animal health issues.

Their work demonstrated that canola is highly digestible (more than 80 per cent) because it is high in crude protein (more than 20 per cent) and metabolisable energy (12 to 14 megajoules per kilogram).

“Sometimes sheep require roughage when grazing canola and need to be introduced to the crop gradually and have access to a plentiful water supply,” Dr Kirkegaard said.

“But the research demonstrated that these issues were manageable.”

The research also showed that cattle were more sensitive to nitrate levels in canola than sheep, which led some growers only to graze cattle on cereal crops.

Another research focus was determining how well the crop recovered after grazing.

This involved investigating the timing and intensity of grazing and the timing of lock-up.

“We showed that removing the animals before the stems had elongated too far was critical,” Dr Kirkegaard said.

“If the animals were biting off too many buds, flowering was delayed into a period when the heat and moisture risk was higher, which often reduced yield.

“Also, if there wasn’t sufficient residual biomass by the time the crop was in its critical period for grain production during flowering, we couldn’t achieve high yields comparable to the ungrazed canola.

“The result was a set of rules-of-thumb around grazing, lock-up and recovery for particular yield targets.”

Researchers wanted to determine where grazing canola had potential in Australia, so computer simulation modelling studies were the next step.

The CSIRO’s Dr Julianne Lilley and Dr Lindsay Bell, working with Charles Sturt University’s Dr Jeff McCormick, determined the potential grazing days and grain yield benefits of dual-purpose canola across high-rainfall areas of Australia.

“They also looked at the likelihood of an early sowing opportunity, which is required by dual-purpose canola,” Dr Kirkegaard said.

“The earlier you sow, the higher the level of vegetative biomass for winter types of canola, which allows for more grazing days before locking up the paddock.”

In 2010, the research was scaled-up to explore the benefit of integrating dual-purpose canola across a whole farm system.

Dr Kirkegaard said another experiment, which ran from 2013 to 2016, involved a series of small “farmlets” where sheep were followed through an entire year and areas were sown to dual-purpose crops in rotation with pasture (canola/wheat/pasture/pasture).

“We demonstrated that if you can graze a crop and still achieve the same grain yield, the paddock-scale profit was increased by $300 to $1000/ha,” Dr Kirkegaard said.

He said other benefits of dual-purpose canola included:

• having the capacity to sow part of the farm early with winter canola;

• increased winter stocking rates, which is useful when trading stock;

• higher animal growth rates during autumn, which allows animals to be turned off earlier or at higher weights;

• pasture spelling while stock is grazing dual-purpose crops; and

• spreading the workload and improving risk management by having the flexibility to harvest the crop for grain if spring conditions are wet or continue grazing or making hay or silage if the season turns dry.