AN investment in irrigation infrastructure is paving the way for greater summer and winter crop rotation, and in turn access to a wider group of chemicals, as Gunnedah farmer James Barlow battles herbicide resistant weeds.
He currently grows a mixture of 70 per cent winter crop – wheat, barley, pulses, durum and canola – and 30pc summer cotton and sunflowers, which he is in the process of moving to a 50:50 mix as new irrigation infrastructure is installed.
As well as the economic and agronomic benefits on offer, a key factor in this diverse crop rotation is the access to a broader range of chemical groups to fight herbicide resistant weeds.
Introducing canola to the crop mix has already improved crop competition against winter weeds and allowed for the use of selective herbicides.
“Rotating back into canola and using selective herbicides have been the keys for our black oats and it certainly has reduced the problem,” Mr Barlow said.
“Being a big crop it out-competes the weeds and they don’t have any chance in that situation. We then follow it up possibly with a summer crop like sunflowers or maybe cotton, so you can spray out the Group A resistant black oats just with Roundup – anything left is then quite easy to kill in a fallow situation.”
The Grains Research and Development Corporation (GRDC) is encouraging the adoption of greater crop and chemical rotations by growers throughout the northern zone in order to minimise the spread of herbicide resistant weeds and to maximise farm profitability.
On his 880–hectare property ‘Mirabinda’, Mr Barlow has discovered Group A herbicide resistant black oats, Roundup-resistant liverseed, and RoundUp and Group A-resistant ryegrass.
“Six years ago we started to see a problem in the cereals where we weren’t getting the results with Axial and Topik especially,” Mr Barlow said.
“It got to the point where we just had to rotate paddocks into a kind of a fallow situation, then summer crop them and then back into canola to gain a decent level of control.”
The problem started in the irrigation drains and spread into the paddocks, with an immediate impact on yield – some crops achieved just 25pc of what would have been expected under the seasonal conditions experienced.
Mr Barlow is moving to secure more consistent yields across a 50:50 split of summer and winter crops by installing nine centre pivot irrigators. This would allow for greater crop and chemical rotation, with the inclusion of cotton to allow for tillage, while deep rooted crops like canola and sunflowers would help keep the soil open and friable.
“Certainly the rotation of crops is crucial. At the moment we’re developing the place and getting more pivots in, which will give me a greater area and greater control of crop rotation, so not only rotating between the winter crops but also with summer crops as well,” Mr Barlow said.
“So it’s then just a management issue – rotation will be key to controlling and getting on top of these weed problems.”
Although still in the early stages of implementing the strategy, the results are already clear.
“I have had one pivot in now for five years and it has proven year after year it can still get as good if not better yields under it using and I’m using 30pc less water than I was before,” he said.
“With irrigation the potential is there to get three tonnes to the acre or 7.5t/ha, which is very doable for sure in the durum. Without irrigation on a normal year you’d be looking at about 4t/Ha.
“And what we’re seeing is basically cleaner crops that’s for sure,” Mr Barlow said. “So with cleaner crops comes better yield and a better bottom line, and obviously crop rotation is good for the soil and micro biology as well.
“So that combination of the crop rotation is certainly helping with everything across the board and certainly paddocks that were quite dirty before are quite clean now, so much so that they don’t even need a selective herbicide spray.”
How to 'grow' quality sunflower oil
AS food manufacturers in Australia and Asia reformulate old favourites like Arnott’s Tim Tam biscuits to be lower in saturated fat, many are turning to sunflower oil as the healthy alternative.
Lucky Interissi, Technical Services Leader, Cargill Refined Oils Asia Pacific says this change has generated an unprecedented demand for sunflower oil.
“There is an opportunity to grow the Australian sunflower industry to produce more quality oil, not only for the domestic market but also to meet the growing demand in Asia,” he says.
The recent decline in sunflower production has seen Cargill, a significant Australian sunflower oil refiner, source the majority of its requirements from overseas.
Traditionally, Australia’s sunflower seed averages up to 5 per cent higher oleic acid than imported monosaturated sunflower seed so Cargill and other processors would like to see the Australian industry grow.
AMPS Moree consulting agronomist Tony Lockrey, suggests that growers establish and grow their sunflower crops with the aim of producing high quality oil seed right from the beginning.
“The key is to set the crop up with the best chance of having enough moisture for a good finish,” he says.
“Adequate moisture is required late in the season for grain fill and oil deposition.”
To achieve this Mr Lockrey recommends planting on wide rows, usually 1.5 m in the Moree district, and planting 30 000 seeds per hectare to achieve a plant density of 25 000 to 27 000 plants per hectare.
He says using a precision planter reduces the risk of double seeds and gaps, to give even plant and head distribution along the row, resulting in even grain size.
“We can’t always rely on much effective rain during the growing season so it is important to have a full profile of moisture at sowing and no subsoil constraints,” he says.
