Cows at a farm in Lincolnshire are being fed a form of charcoal in a bid to lower harmful emissions.
Farmer Richard Copley is adding biochar to the feed at his cattle farm near Grantham.
It is part of a trial looking at whether the substance can reduce methane emissions and make cattle dung less harmful to waterways.
Dung samples are taken from the cows and examined by scientists at Coventry University.
Mr Copley said his cows were happy to eat the charcoal, which is produced by heating wood to high temperatures for several hours.
"They instinctively know what is good for them," he said.
Talking about the research, he said: "We've got to feed people but if we can reduce those emissions along the way all the better for me."
Donna Udall, who is part of the research team which studies samples from the herd, said she hoped other farmers would see the benefits and try biochar with their own herds.
She said farmers were often unfairly criticised over their impact on the environment and the trial showed they were doing their bit.