'Fast' trial shows up need for liming

25 Nov, 2013 01:00 AM
About 40 farmers travelled to Darkan to sees the results of the Hy-Lime treatments in a barley crop.
About 40 farmers travelled to Darkan to sees the results of the Hy-Lime treatments in a barley crop.

ABOUT 40 farmers travelled to Darkan earlier this month to investigate a barley crop that, in just a few years, had transformed from a weed-ridden headache to a crop so thick you could almost walk on it.

Robbing WA farmers of between $300 and 400 million each year, soil acidity can be - and has been - catastrophic to Wheatbelt farmers holding off on liming.

But an application of lime was all that was needed to dramatically improve the availability of soil phosphorus to the barley crop and make Darkan farm owner, Bruce Taylor, one happy and relieved farmer.

According to Department of Agriculture and Food (DAFWA) development officer Greg Shea, the crop was located on a high phosphorous-fixing loamy gravel, typical of soils in the area, which are characterised by increasing pH down the profile.

In a bid to generate a rapid increase in pH, three applications of very fine, high-neutralising, value-hydrated lime (Hy-Lime) was applied by hand at two tonnes a hectare.

Mr Shea said the high lime used was relatively expensive and impractical to apply, but worked much quicker than calcium carbonate.

"Instead of waiting years for the same effect, we wanted to get in and show the effect quickly," Mr Shea said.

"This stuff is so fine that in less than a year, you get a result instead of waiting."

While he doesn't suggest growers repeat the exercise, he said it was an adoptable practice.

"We tell people to use the best quality lime they can get a hold of," he said.

According to Mr Shea, one of the Hy-Lime treatments was immediately incorporated to a depth between 15 and 18cm using a heavy disc plough, while the other treatment was left on the surface.

All deep-ploughed treatments were then lightly scarified to smooth out the seed bed.

"Farmers need to realise how important it is to get into liming programs," Mr Shea said. "Time is of the essence.

"The paddock behind Bruce's treated paddock is bare.

"There is no crop there, which goes to show that the sooner you get on to it the better."

Mr Shea said Mr Taylor had been behind the eight ball and taking a loss of one magnitude or another for years.

"He was putting the fertiliser on where you're getting a very marginal return from it because the roots of the crops are stuffed by the acidity.

"Fix the acidity and then the fertiliser you put on is of use."

Mr Shea said that while lime can be a significant financial investment on the farm, the quicker the dollar returns the better.

"The growers who attended the field day saw a spectacular response to lime in the barley crop sown this year with a large reduction in effect on the ryegrass population in the limed plots," Mr Shea said.

"Imagine what the yields would be like around the place if these light land soils had their acidity corrected."

ConsultAg agronomist Garren Knell said the important priority was to get lime into the program and then gradually get experience with the practicalities of deep ploughing.

He said the seedbed after ploughing was not suitable for seeding into, especially if seeding canola where depth control was so important.

"The ploughing was rough on my equipment and made a mess in the paddock with old tree roots being dug up in the process," Mr Knell said.

Retired DAFWA researcher Bill Bowden, who instigated the trial, said low soil pH could result in toxic aluminium levels in the soil and these levels could cause root pruning which impaired the ability of crops to take up nutrients which are immobile in the soil.

Monitoring 184 sites in the Wheatbelt, the GRDC-funded Focus Paddock project has found that most crops might not be responsive to phosphate and have critically low pH levels.

"Lime is urgently required, there's no way around it," Mr Shea said.

"Farmers are pouring on all these inputs and not getting the yield they expect, which is a real symptom that there is a major problem with acidity."



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