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A group of Tasmanian dairy farmers is hopeful tiny organisms in the soil could soon offer a cheaper, climate-friendly alternative to synthetic fertiliser.
They've made more than 500 hectares available on eight farms for a pasture trial to measure whether microscopic soil organisms can supply nitrogen, phosphorus and potassium (NPK), the three essential elements in most commercial fertilisers.
Agronomist Hiren Bhadani proposed the experiment three years ago while working at one of the farms now in the trial.
he said.
A student's idea takes root
The then-master's research student was working at George Rigney's property in Cressy, northern Tasmania, to help pay his way through university.
George Rigney and Hiren Bhadani say the trial has improved soil pH and pasture growth. (ABC Landline: Pip Courtney)
"We were spreading urea throughout the year with one operational tractor every day going with the urea, and that's not really good for the soil or not good for the environment," Mr Bhadani said.
Witnessing the daily routine got Mr Bhadani thinking about potential solutions, like applying microbes.
"If we reduce the synthetic urea application, we will reduce the greenhouse gas emission in the environment, which is very, very harmful to the climate," he said.
Microbes in the soil help supply nutrients such as nitrogen, phosphorus and potassium for pasture growth. (ABC Landline: Pip Courtney)
He also estimated reducing urea use by 25 per cent would save the dairy $100,000 a year.
Hiring Mr Bhadani as a farm worker proved fortuitous for Mr Rigney.
Mr Rigney said.
Sparked by an after-work yarn with Mr Bhadani about microbes and cricket, Mr Rigney agreed to a trial to see if soil microbes could improve soil health, boost pasture growth and cut the farm's reliance on urea.
Mr Rigney says using microbes has reduced his fertiliser bill and cut greenhouse gas emissions. (ABC Landline: Pip Courtney)
"[There are] millions of microbes in just one milligram of soil, but out of those millions we have only a few species which are very important for the soil, and me and George are working on those kinds," Mr Bhadani said.
How four microbes are changing the soil
Mr Bhadani has been testing four species imported from India, which are sprayed onto paddocks in liquid form.
Two take nitrogen from the air and put it in the soil, while the remaining microbes unlock complex forms of phosphorus and potassium, making the nutrients accessible to the plants.
Mr Rigney and Mr Bhadani discuss soil health at the Rigney family dairy farm in northern Tasmania. (ABC Landline: Pip Courtney)
Mr Rigney said.
The pasture growth and reduced soil acidity shocked both men.
"We're actually growing more grass with 25 per cent less fertiliser and soil pH is up," Mr Rigney said.
When the trials began three years ago, the soil contained none of the four microbes. Now, their concentration is about 35 per cent.
Mr Bhadani proposed the trial while studying for his master's and working on the farm. (ABC Landline: Pip Courtney)
"They multiply by themselves … our aim is to get to 50 per cent microbes per gram of soil, and then we're going to call that fully stocked," Mr Rigney said.
"That's our saturation point. We don't think that we're going to get any more benefits after that."
Mr Bhadani predicted significant savings.
"In the next five years, if the whole area is under [the] microbes trial, it will definitely reduce 30-to-40 per cent of the synthetic urea … that's a big, big amount for the dairy business."
Early signs show healthier soil
As word of the trial spread, other dairy farmers asked to take part.
Before signing up, Troy Ainslie, manager of Woodrising Dairy at Cressy, was sceptical.
He figured if they worked, microbes would already be widely used.
Troy Ainslie was initially sceptical about using microbes but now plans to expand the trial. (ABC Landline: Pip Courtney)
"You have a bit of apprehension [asking], 'Why is it not done already then?' Mr Ainslie said.
After the success at Woodrising, the farm's owner Compass Agribusiness Tasmania is considering using the microbes on its five other dairy farms.
The trial's early success hasn't just convinced local farmers; it's also sparked interest from industry leaders.
The Rigney farm supplies milk to dairy giant Fonterra.
Pressure to reduce nitrogen losses
Fonterra is watching the trial closely as pressure builds worldwide for farmers to apply less urea to pastures.
The milk company's agronomist, Richard Rawnsley, said nitrogen losses were a concern for the industry.
Cows grazing on the Rigney family’s property, where pasture growth has improved despite using less urea. (ABC Landline: Pip Courtney)
Dr Rawnsley said.
"If we're losing it up [into the air], that can be lost as nitrous oxide, which is a greenhouse gas that we don't want. And nitrogen can get down below our root zone and into our waterways.
"It's a new area of science and understanding, and it's great to see what Hiren and George and the team are doing here … I think it's very exciting."
While the trial is still in its early stages, Mr Bhadani hopes, with Mr Rigney's help, they might one day be able to manufacture the Indian microbes under licence on the dairy farm.
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