Firefighters were called to farmland in Great Chishill last night after fly-tippers dumped a load of rubbish and set it alight.
Crews from Sawston and Royston attended the blaze which started about 10pm at Rectory Farm in New Road.
Firefighters used two hose reels to extinguish the flames, before returning to their stations by 1.30am.
The area was reinspected at 9am today.
Officers have said the cause of the fire was deliberate. Anyone with information should contact police on 101, go to www.cambs.police.uk to submit an online report or call Crimestoppers on 0800 555111.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here