by Bill Crabtree, Agronomist
Aquifer liquid N combinations are gaining traction across WA, but Bill Crabtree explains why the risks – particularly in dry conditions – are just as important to understand as the opportunities, and what the 2025 Mindarabin yield data really shows.
Aquifer liquid N combinations: the risks and opportunities in WA wheat
Aquifer is gaining widespread farmer acceptance as the most reliable, affordable and easy to use wetter, so let’s continue to talk of the opportunities and risks.
There is a lot of marketing from competitors boasting improved plant establishment, but strangely they do not show grain yield data. Farmers get paid for grain, so such marketing is evading yield data.
Our 2025 wheat Mindarabin trial showed a poor correlation between plant counts and grain yield. This is unusual and it says that some very interesting humectant effects are happening – more than just establishment.
The blue dots are Aquifer placed with the seed at 1, 2, 4 or 8 L/ha while the black dots are SE14 at those rates also and placed with the seed. The orange dots are a different wetter-humectants or testing placement on top of the furrow.
Aquifer gave the best plant numbers and the best yield. Recent farmer meetings shows strong support for Aquifer and why farmers are swinging over to Aquifer from SE14.
Can UAN and Aquifer go together?
Yes, and many farmers are doing this at modest rates of 20-30 L/ha, but there are opposing forces at work. If you are in a dry area and you want to get the crop up on subsoil moisture then perhaps it would be smart to back off on the N – you can add that later when doing early post emergent weed control.
Aquifer is effectively a liquid organic matter (or clay) and it will biodegrade. It draws moisture to it and lets most of it go for the plant. I am now convinced it has a useful role on more soils than just water repellent ones. It draws moisture out of subsoils and dews and pulls it to the seed.
On minimal moisture UAN will make the seed zone salty and will release damaging ammonia as it slowly wets up. If moisture is plentiful at seeding then that risk from 40 L/ha of UAN will be greatly reduced. We do have liquid NBPT that can reduce the risk of the damage also.
If you picked up good rains in February in the dry farming area it would be best to drop the UAN out and just go for germination. Unless of course you see good rains on the way and the soil is very dry. Early emergence is the secret to high potential yields.
TC Mitchell and March/April Sowing
If you received good rains from tropical cyclone Mitchell, then you have a chance to do something special on part of your wheat program. As a past NE Morawa farmer myself who used the long coleoptile wheat Magenta, I would regularly plant it onto receding topsoil moisture after a summer rain in my loamy soils in April and it always yielded the best.
When chasing moisture, I would always put the seed deep and at the bottom of the slot. I did this by switching my fertiliser opener with my seed opener on my SeedHawk. This avoided placing the seed in fluffy drying soil behind a closer plate. I had a chat with Callum Wesley about his experience, and he found that placing seed in the usual location caused some fluffing and drying. So, try switching your openers. Then of course it is safer with a parallelogram so you can be centimetre perfect.
But if you have a liquid system then you could place Aquifer Sustain (as it has more humectant) at just 1 L/ha with the wheat seed and improve the suction power to the seed and get a more reliable establishment. We know that this subsoil moisture is slowly drying as it moves to the surface to evaporate. The humectants can intercept this, hold it and give the water to the seed.
If you don’t have a liquid system then you could coat 2 L of Aquifer Sustain per tonne of wheat along (diluted with water) along with your fungicide. This is a copy the work of Dr Geoff Anderson from the Northam DPIRD office – he is happy to take your call on (08) 9690 2104. I am also happy to come and chat to a group of neighbours with you also.
Get the right variety
Two things to consider in this brave new attempt to get reliable autumn wheat establishment on fleeting deep summer moisture. They are coleoptile length and day length sensitivity. Magenta has a 9 cm long coleoptile, and I could plant it from 13th April onwards at NE Morawa as the frost risk had faded by late July when flowering would start for me.
The other variety that I have confidence and my favourite while the moisture is still within humectant reach is Mohawk from Longreach, bred by Kevin Young. It needs to be out of the ground by 15th April and sown in March anytime is okay. This has a medium-long coleoptile.
Another variety that would likely be a good fit is AGT-Hamelin as it can be sown in April and will still yield well if sown (or emerges) in May. But note it only has a medium coleoptile. This is what makes the Aquifer Sustain valuable. We plan to do trials on these ideas in March.
Feel free to give me a call to talk it through for your situation on (08) 9356 3445. For product purchase contact sales@4farmers.com.au