Dieback: It's all in the soil

Northern experimentation links poor soil health to dieback root cause

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Soil health is the key to managing dieback in pasture and horticultural systems, according to a farmer from Gin Gin who has been experimenting with organic ways of treating the problem.

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A typical pasture dieback scene, from Rob Pagano's Malanda cattle property, prior to experimentation with a humate biostimulant. Pictures supplied.

A typical pasture dieback scene, from Rob Pagano's Malanda cattle property, prior to experimentation with a humate biostimulant. Pictures supplied.

Soil health is the key to managing dieback in pasture and horticultural systems, according to a farmer from Gin Gin who has been experimenting with organic ways of treating the problem that's emerged since the early 1990s.

According to Bob Alder, continued overgrazing and a reliance on chemical fertilisers has stripped minerals out of the ground, which creates a lack of soil microbes that insects and fungi are able to exploit.

A marine engineer by trade, Mr Alder has been doing his own research and development work on his 40 hectare lifestyle block after conversations with local farmers about their dieback issues piqued his interest.

As a result he has devised a humate biostimulant he calls RC3, which a Malanda cattle producer and an agricultural consultant in the Northern Territory each credit with halting and reversing serious problems of their own and others.

"I'm not into chemicals, I was looking at organics," Mr Alder said, explaining his carbon chemistry mix that incorporates humic acid and sea minerals that are the byproduct of making salt.

"In the plant world anything that's stressed is open to infection.

"Everything relies on organic material going back to the soil - when you harvest, that remineralisation doesn't happen.

"And every time you put nitrogen out at 150kg/ha you kill 90 per cent of soil microbes.

"So many millions of dollars have been spent on this when there's an easy fix - it's soil health that fixes the grass's health."

Fingers have been pointed in recent years at mealybug as the culprit as far as grass dieback is concerned, however other scientists believe the white ground pearl insect in its cyst stage could be the cause.

Malanda cattleman Rob Pagano said he didn't think the mealybug was the main problem.

"I've dug holes everywhere and not found mealybug but I was still getting dieback," he said.

If it was definitely mealybug, how come dieback went to a four-barb fence and stopped - Malanda grazier Rob Pagano

"It's got to be something that stops at the fence and that's cattle."

After trialling Mr Alder's RC3 product over the last 12 months, followed by a variety of grazing regimes, he is taking a wait and see approach but has noticed that his soil has more worms and worm eggs.

"I'm not saying he will fix it but I take my hat off to Bob," Mr Pagano said. "He's not a chemist or a scientist but he's the only one who's pulled this apart under a microscope and documented changes in the soil."

He also complimented Mr Alder for looking into the problem in a North Queensland setting, saying most research trials seemed to be taking place in central Queensland.

The value in venturing north was because the higher average rainfall meant that pasture had a chance to regenerate and give more results.

"We need more people up here to do sampling of soils and leaf matter - there are all different fields to work in," he said.

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Bio-Logical Ag consultant Keith Dankwerts, based in Toowoomba, said he thought the product, and Mr Alder's concept, was on the right track.

"The program he's putting down, I think is working," he said.

"The first time I visited him I found mealybugs but the pasture wasn't dying.

"That indicates the product is working, but I've not done any trials."

From what he had observed of Mr Pagano's situation in Far North Queensland, Mr Dankwerts said Mr Alder's program had eradicated a fairly severe insect problem through its combination of plant growth stimulation and encouragement of microbial activity.

Another view of the dieback on Rob Pagano's Malanda property.

Another view of the dieback on Rob Pagano's Malanda property.

Dieback has emerged as a problem in parts of the NT in recent years, around Darwin particularly but also in the Katherine region, according to 864 Agricultural Services spokesman Ian Golding.

He's been a mango farmer in the NT for 25 years and said probably 25 per cent of trees in the Darwin region, or between 250,000 and 300,000, were affected.

"Surveys done by the DPI show it's increasing - it's been a growing concern for the past three to five years, and the only cure is changing business practices," he said.

He's been using Mr Alder's product on mango, banana and papaya trees, and on watermelon, pumpkin, eggplant and grape vines for the last eight to 10 months. The commercial trials have involved over 100,000 trees.

"There's been a positive result, not 100pc, in the past six months," he said.

"The trees that have recovered are all showing a really good flowering for this time of year.

"It's a really integral part of treating dieback; it seems to knock out diseases and then supply nutritional needs."

Getting minerals right

Mr Alder said a company at Katherine that had used humate and sea minerals and then put plastic down and sprayed with RC3, but no conventional fertiliser, had picked watermelons at a rate of 50 tonne/ha, compared to the usual 25-27t/ha.

"And rather than pull up the plastic and start again, they resprayed and they're looking at 50t/ha again," he said. "They've saved $14,000 in plastic plus the savings on fertiliser and chemicals."

Mr Golding said that even if crops didn't have dieback they would benefit from use of the product, in that it improved fruiting quality as well as nutritional value and flavour.

"It's chalk and cheese when you get the minerals right," he said. "It's a good product to help farmers transition to more resilient farming systems."

As far as blaming fungal problems for dieback, he said that was secondary to the stress plants were going through.

Mr Alder agreed, saying the dieback at Malanda had worsened when fungus allowed wireworm and curlgrub in.

"It's a diverse and complicated thing to try and fix," he said.

"It's not about the expense because it doesn't cost as much as fertiliser.

"It's as much about convincing farmers to try something out of the box."

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