Officers received a call at 20:30 on Tuesday 30 August 2022 after the Fire Service attended to a large fire between Brigg and Broughton.
Detective Constable Scott McCreight is investigating the incident.
DC McCreight, said:
"This was a very large fire which was spreading at an alarming rate following the recent extensive dry weather we have had. £30,000 worth of damage was caused and we believe this fire to have been started deliberately."
DC McCreight is appealing for the public's assistance, and added:
"I would appeal for anyone who may have been in the area at the time, has dashcam footage or any information that would help with our enquiries. If you can help with our investigation, please call us on our non-emergency number 101 quoting log 545 of 30 August 2022."
Alternatively those with relevant details can contact CrimeStoppers, anonymously, on 0800 555 111.