Essentially, the walk away option was never there,” says renowned cane farmer Robert Quirk of the 1987 mass fish kill that wiped out almost every living thing in the Tweed River.

The kill caused the public and fishing industry to do the almost unthinkable and turn on their own growers.

"We're farmers, we're of the land, and we just love it,” Mr Quirk said this week.

"Not to mention, if we'd walked away it would have been horrendous for the environment. The river was sterile from Murwillumbah for 30km. It killed the fish, the bloodworms, the prawns - everything. And it came after we had a rain event similar to the one we had this year on the back of a long, dry period.”

Tweed mayor at the time Max Boyd says community reaction demanded the council act.

"I was certainly very keen to try and find the problem to what was killing the fish,” Mr Boyd said.

"It was obviously a very serious problem and we needed a solution.”

The court of public opinion blamed the cane farmers and their pesticides and herbicides. But Mr Quirk says in the 30 years since, they've learnt the real issue had been caused some 10,000 years earlier when much of the region's rural land had formed part of the sea floor. When ocean levels dropped, the remains left toxic deposits that produced acid sulphate soil - "some of the nastiest in the world”, according to one soil expert.

Mr Quirk says heavy metals like aluminium and iron were flowing into the waterways and killing fish. The aluminium dissolved the gills of the fish and gave them "something like a very heavy cold”.

"They're actually gasping at the surface of the water and it gives the impression it's low-dissolved oxygen in the water,” he said.

"But it's actually that they're suffocating because they can't breathe.”

The story since is how a humble Tweed farmer reacted to the disaster and from it discovered a secret formula that somehow turned toxic land fertile.

"What we have developed is now recognised as global best practice for the cane industry,” he says of the 30-year trial-and-error experiment to get to the bottom of why the fish were dying and how to not only fix the problem but ensure the long-term future of the cane industry.

"What I'm (recognised for) is more land management and how to build soil carbon, which is a process that involves taking the carbon out of the atmosphere and putting it back into the soil.”

When Mr Quirk first floated his practices in a paper at an international conference his claims were rejected because no one else had been able to do what he did. "I said, 'well, come and have a look sometime because we've measured it and what I'm saying is correct'.”

Eventually his practices were accepted and his work in sustainable farming celebrated.

"Mr Quirk's love for the soil, his love for farming and his live of espousing that to the wider community deserve the international acclaim and recognition he has been given,” Auburn MP Barbara Perry told the NSW Parliament in 2008.

"Not only is he prominent and leading the way in relation to sustainable farming for the future but he also has contributed to the community in so many other ways.” A former head of the Tweed's Canegrowers Association, in recent years Mr Quirk's farm has become something of an attraction to scientists, government departments, farmers and international visitors. He's had people from 70 different countries come to his Duranbah property and has flown to 30 nations to share his knowledge.

The 72-year-old says he'll never walk away from farming because he can't.

"I love farming and I want to keep doing it as long as I can,” he says. "People say, 'why don't you retire?' and I say, 'And do what?' This is not only my life it's my hobby as well. It means something to me. It gets in your blood.

"The first thing you do when you get up in the morning is look out the window and make sure everything is alright down there and my wife says, 'What are you looking at?' and I say, 'I just have to check everything is alright'.”