Growers informed about best sowing practices for canola crop establishment

About 100 farmers, argonomists and other grain industry stakeholders from across the state turned out to the GRDC Crop Establisment Showcase, held at Andrew Thomas' property in Wynarka, where both canola and cereal crop trials are underway.

CSIRO Farming System researcher Kenton Porker was one of the guest speakers. He said the day was a good chance to reflect on what had been learned about the late season and what croppers could do in future seasons like this one.

"We have just experienced one of the driest autumns on record," he said.

"This made it really difficult to get canola crops established on time, so there is a lot of angst about what that might mean for yield this season.

"So we have been looking at what growers could potentially do in these hot, dry autumns to establish canola better."

Mr Porker said the fundamentals of what causes a crop to establish is water and temperature, but soils strength was also an important factor.

"So depending on where you are, whether you're on a clay soil, whether you're on sandy soil, the thresholds for those things are different," he said.

"Our research is trying to understand those fundamental things, because then if you can understand them, we can actually work out ways to set up your system to address the challenges that might come."

Mr Porker said there was also a lot more data these days on how much temperature played a role.

"It is something we probably haven't thought about as much," he said.

"There is really good evidence to say that a little emerging canola seed can actually tolerate quite warm temperatures, up to 35 degrees, but once you get to 37-38 degrees, the rate of germination declines rapidly.

"And it's not uncommon these days to get four or five days above 30 degrees in April.

"We are now learning in the topsoil of sandy soils, the temperatures can be up to 10 to 15 degrees hotter than the actual air temperature.

"So we can often be trying to get a little seed to emerge in pretty hot, hostile conditions - that's been a big learning - to think about where we are putting the seed in relation to temperature in the seedbed."

Mr Porker said a potential way to avoid that heat could be to sow deeper.

"So some of our research is starting to focus on that now - how deep can we sow canola for it to establish in those early, hot, drying topsoil conditions?" he said.

Mr Porker said deep sowing was potentially more suited to sandy soils, compared with more "strong" clay soils.

"Sowing at depth works if you keep the soil loose and fluffy on top, then you can seed at depths of 5cm or even more," he said.

"But a clay soil or heavily compacted soil can reduce the amount the canola can establish from depth.

"A big learning from both the wheat and canola trials, was that as soon as you start to get deep, you then have to rethink your seeder set up."

Mr Porker said another surprising realisation out of the trials was how little water was needed to grow a canola crop.

"We saw you could establish a crop on 5mm of water, sown around Anzac Day, April 25, on sandy soil," he said.

"I think that's cause for optimism to make the most of rainfall events.

"If I thought I needed 10mm of water to establish a canola crop - that's about a one in three year event to establish a crop in April.

"But if I knew I could establish a crop on 5mm of water, the increase in likelihood is about 50pc of seasons, so the opportunity to do it rapidly increases if we can."

Mr Porker said ongoing soil moisture was also important, and this season's long dry spell after the traditonal season start wasn't ideal.

"Usually I'd say if it was seven days or even two weeks after that, you'd usually be okay," he said.

"But this year was it was almost 42 days until we got another decent rain event, that was too long.

"And some of those crops, there are some plants there, but not enough."

Mr Porker said the ideal timing for canopy closure was late June, to have the crop "humming" through July/August.

"The reason we want canola crops to establish early is that we know that we have to build biomass to get yield," he said.

"The problem we're facing with this year's late break is it's now cold, and I just don't know how we're going to get the growth to build the grain number when we want it.

"Canola's critical period is just after flowering, and that's when you want to be growing as much biomass as possible.

"But in the Mallee that typically starts in late July, so from a late-sown crop, I don't know if we're going to have the right development stages to make the most of that.

"That's why seeding canola between April 10 and 25 is ideal. Anything sown after that is of concern, and why you start to see that yield penalty after May 10.

"You just can't grow enough biomass when you want it."

On a more positive note, Mr Porker said it was good to see canola crops establishing on less water "than we ever thought we could".

"We are seeing examples in cereals and some other crops that they can establish in the absence of any autumn rainfall," he said.

"To me, that's the ultimate goal. Imagine if low rainfall growers could establish a crop in the absence of autumn rainfall - it sounds like a pipe dream, but it's actually true, because we're getting better at storing water in our system.

"So farmers can be more confident knowing there is solutions out there. There's just genetics and engineering things that we're going to have to do, and that's what this day was hoping to show."