A farmer has died after receiving burns in a large grassfire which threatened homes about 100 kilometres north of Adelaide on Friday.

The Country Fire Service (CFS) said the Nantawarra fire had burnt in a south-easterly direction towards Balaklava, Whitwarta and Bowmans north of Adelaide.

The 38-year-old man was a CFS volunteer with the Mount Templeton brigade and suffered severe burns fighting the blaze.

CFS state coordinator Brenton Eden said the man was airlifted to the Royal Adelaide Hospital, where he died on Friday evening.

Two others were also injured, including another CFS volunteer, in what Mr Eden said was a tragic way to start the fire danger season.

"It really doesn't matter whether they're a volunteer or a paid firefighter, we have no desire to see any injuries on our fires. We aim for a zero injury summer but clearly we've started off today with three."

Another local Tim Dickson was on the scene soon after the accident occurred.

"We were putting wet towels on [the man] and sprinkling him with water until the ambulance got there," he said.

"He was just a great bloke, down to earth, and wouldn't hurt a flea.

"Just like all neighbours do when you see smoke, you hop in the ute and go to help, and that's what he would have done.

"You never think you won't come home."

Lentils a 'higher fire risk' during harvest

The CFS believes the fire started in a header being used to reap lentils.

Grain Producers SA chairman Garry Hansen said lentils were known to be a higher fire risk during harvest than other crops.

"Last year we saw a number of instances where the risk of fire increased significantly when farmers were reaping lentils and everyone at that stage was putting it down to some seasonal conditions," he said.

"Maybe those conditions are going to be occurring every year."

Mr Hansen said the lupin dust and residue was highly combustible and built up on the header and around the exhaust.

He said the dust was also known to spontaneously combust at sub-exhaust temperatures.

"A lot of guys reaping lentils reap downwind so they can smell any smoke, which gives them some pre-warning, but sometimes that's not enough," Mr Hansen said.

"A lot of farmers have got someone else in the paddock if their reaping lentils, and have extra water availability, but it's very difficult if you're a sole operator.

"Maybe we have to sit down with the CFS and come up with some solutions, come up with some protocols to put in place so we can reduce the incidents of fire when farmers are reaping lentils."

Around 1,800 hectares of stubble and scrub were burnt in the blaze, which had been fanned by strong winds.

Water bombers were called in and an additional three strike teams joined the 55 personnel on the ground.

The fire initially posed a danger to homes, but Mr Eden said it was contained by mid-afternoon.

Bureau of Meteorology senior forecaster Matt Collopy said wind gusts had reached up to 60kph in the Balaklava area.

Fire cause under investigation

CFS chief officer Greg Nettleton said a number of fires had been sparked during lentil harvesting but authorities were still investigating the exact cause of Friday's blaze.

"We were aware of that last year and we've had a couple of fires this year as well, but what it really means is that with every activity that you're doing in the bush during the summer, you need to be vigilant and careful," he said.

He said the deceased CFS volunteer and farmer had left behind a partner and children.

"Obviously the local brigade and the neighbouring brigades up there are quite shocked by what's happened," Mr Nettleton said.

"Firefighters are a big family and it won't just be those local brigades that will feel this. Right across the CFS family, there's shock and mourning as a result of this."

For more information about bushfires, check the CFS website or call the Bushfire Information Hotline on 1300 362 361.