A groundbreaking trial that started 20 years ago fertilising Queensland cotton farms with treated human sewage has become so popular more than 100 farmers are now on the waiting list.
Farmer Stuart Armitage, from Dalby in southern Queensland's Western Downs, was one of the early users.
He admitted he was "pretty dubious, being what it was", but became a convert after his first crop.
"When we saw we could apply this product and grow exceptional crops, that was the key to me," Mr Armitage said.
"It just seems to have everything a plant requires so we were getting the balance that we weren't able to get with chemical fertilisers."
Reducing chemical fertilisers
Farmers who use the treated sewage, called biosolids, report improved water use efficiency, a drop of up to 95 per cent in chemical fertiliser use, and increased yields.
"We're not using any chemical fertilisers this year [and] so far we haven't sprayed any cotton.
"We're probably going to get it through on two irrigations, maybe three if it doesn't rain, and that can't be replicated anywhere else in the world."
The financial benefits of using biosolids got Mr Armitage over the mild disgust of using human waste, and the bad smell.
Human waste no longer wasted
When the trial started in the early 2000s, some south-east Queensland councils were dumping biosolids in old mine shafts.
Now many councils in Queensland and New South Wales pay recycling business Arkwood to truck it to cotton, grain, vegetable, and beef operations lucky enough to be on its list.
"Our most northern plant is a little town called Coen right at the top of Queensland, and we go right down to Eden on the far south coast of New South Wales, and do most plants in between there," Arkwood's Brendon Clarke said.
"Occasionally, we work in Victoria and even Tasmania.
Mr Clarke's fleet of trucks cart 80,000 tonnes of biosolids from the City of Gold Coast's four treatment plants to farms every year.
The council is pleased its waste is no longer being wasted.
"Brendon would take more if we had it. The Gold Coast is growing faster and faster, so the more we produce Brendon can take as much as he likes."
Long waiting list
Population growth is the only solution to the long waiting list of farmers who were late to the "poo party".
Dalby farmer Nic Clapham's father was the second in the region to try biosolids.
He said his soils are now more friable, hold more water, and the organic nutrients are retained for years.
He noted he was able to double crop paddocks this year because of his use of biosolids.
"We generally rest the ground for 12 months, but because we got some rain when we were harvesting wheat we had the opportunity to go straight back in and plant corn."
Agronomist Matthew Holding says farmers using biosolids are really just going back to ancient farming methods.
"And surprise, surprise, it works because it's got all the micronutrients like zinc, cobalt, copper, and macronutrients like nitrogen, potassium phosphorus.
"Everything that we need in our bodies is also in this."
Increasing soil carbon
Soil carbon is now a hot topic in agriculture, but when biosolids first started being used, farmers knew little about the benefits of boosting carbon levels in soil.
But recent tests by the University of New England show they had unwittingly done just that.
On the Armitage's property, carbon levels doubled.
What excited Mr Holding was the potential that increased soil carbon had to improve farm operations' resilience to the financial and environmental impacts of climate change.
Stuart Armitage believes he will be able to sell his cotton to eco-conscious buyers prepared to pay more for sustainably farmed cotton.
"We're actually making the land better, and this I hope will give us accreditation into some of the overseas markets," he said.
Mr Armitage said there had been a few light moments — like calling the police to check out an odd plant in his cotton.
Watch this story on ABC TV's Landline at 12:30pm on Sunday, or on iview.
