The fire next to his own property on the South Asutralian island was put out thanks to his efforts on the grader, other farm fire units and Country Fire Service volunteers.

His initial thoughts when mopping up the fire was that months-old residual coals in a old pile of earth and logs were responsible, but he now believes a more recent lightning strike could have struck the pile.

A CFS spokesperson says while not impossible, a fire burning for 11 months was unlikely.

There were lightning strikes in the Newlands area a few weeks back, with the possibility that this was the cause after the old pile smouldered for weeks rather than months.

There had been cases of tree roots burning underground for months, and there was even a hazard reduction burn on KI in August that reignited several weeks later, the spokesperson said.

Mr Halloran has been spotting and fighting fires on Kangaroo Island for more than 45 years, going to every major fire over that time, either in his plane or heavy machinery.

He says Saturday's grassfire spread from a large pile of earth and logs pushed up from a paddock clean-up in 2017 into about a 20-metre-long and two-metre-high row.

"I spread this out so they could black it out and found in the centre a quite a large area of hot, soot-type ground," he said.

"It could have been from a more recent lightning strike or could have been from months ago from the January fires."

There had been another unexplained grassfire off Mays Road that flared a few weeks ago, he said.

When it comes to fire, the farmer, heavy machinery operator and pilot has just about seen it all.

So when he spotted smoke rising from paddock near his home on East West One Highway about 2pm on the Saturday, he naturally raced to the scene.

He responded with two his Caterpillar 12G motor graders, one of which was driven by his friend Dave Frazer.

On the way, he called local Kangaroo Island CFS Group officer Terry May to alert him.

They immediately started putting in an earthen fire-break around the perimeter of the fire while a farm unit stopped the flames from spreading into a creek line.

Mr Halloran said the Western District CFS brigade upon arrival was very concerned about the fire escaping into thousands of acres of unharvested grain crops.

"It didn't look good at the time and the fire farm unit did a fantastic job preventing it from spreading into the creek," he said.

Fortunately, the farm fire units, CFS volunteers and heavy machinery operators worked together to contain the fire.

While he had heard of fires burning in peaty ground reigniting after three or four months, he had not heard of a fire possibly burning this long and then reigniting.

After the initial fire-fighting effort last Saturday, he returned with his front-end loader to tidy up.

It was then that he could clearly see the recently active powdery ash at the centre of the pile that seemed to sparked the grassfire.

He finally got back home with the loader at 5pm, another day's work done helping fighting Kangaroo Island's fires.