Scientist Colin Andrews says 17 years of work has revealed that about 80% of the formations are man-made.
Scientist Colin Andrews says 17 years of work has revealed that about 80% of the formations are man-made.
But he believes that magnetism may account for the rest, which display a simplicity of form compared with elaborate, beautiful patterns of the "hoaxes".
Dr Andrews believes a mysterious shift in the magnetic field gives rise to a current that "electrocutes" the crops forcing them to lie flat on the ground.
Summertime feature
The known hoaxers, artists who spend hours trampling fields with footboards attached to a length of rope, say the public does not believe in scientific explanations.
Crop circles are a regular summertime feature of the UK arable landscape, particularly in Wiltshire and the West Country where there are a number of ancient sites.
Designs in the flattened wheat, barley and corn become more elaborate each year, fuelling the debate over who or what is responsible for them.
Explanations have ranged from freak weather conditions to alien visitors. But Dr Andrews, funded by a grant from the Rockerfeller Institute in the US, believes he is closer to the truth.
'Natural' creations
He has hired private detectives to track hoaxers and now says he can rule out 80% of the formations. He claims the less elaborate designs are the "natural" creations caused by a three-degree shift in magnetic field lines.
Dr Andrews, who plans to publish his findings later this year, says more work still needs to be done his theory.
Self-proclaimed hoaxer John Lundberg said no-one would ever believe a scientific explanation for crop circles because people want to believe it is something more mysterious. "The public don't want it explained," he said.
Most mainstream scientists believe the only explanation for crop circles lies in the footboards of hoaxers.