A farmer cut off his own leg with a pocket knife after it became trapped in a piece of machinery on his isolated land.

Kurt Kaser, from Nebraska, was unloading corn last month when he climbed out of his truck and accidentally stepped on the opening of a grain hopper.

The 63-year-old said he could remember telling himself “this ain’t good, this is not good at all” as he tried and failed to pull his leg out.

With no mobile phone near him to call for help and the knowledge that no one would come to his aid, the farmer of 40 years made the agonising decision to amputate his own leg.

He told KETV: “I thought ‘how long am I going to stay conscious here?’ because I didn’t know what to expect.

“Then I felt it jerk me again and I thought I it was going to grab me again and pull me in further.

“I had my pocket knife and I thought ‘well, the only way I’m getting outta here is to cut it off’ so I just started sawing on it.

Kurt Kaser, 63, amputated his own leg with a pocket knife after it became trapped in a grain hopper on his isolated farm in Nebraska, US. (KETV)

“When I was cutting it, the nerve endings I could feel them just ping every time I’d start sawing around that pipe and all at once it went and let me go so I got the heck out of there.”

After freeing himself, Mr Kaser then had to crawl 150ft across the farm to the nearest phone to call for help.

He said he could not remember much pain or blood but he never lost consciousness and could recall the journey to the hospital.