A 22-year-old man has been cautioned for possession of cannabis.
Police seized a vehicle and cautioned the Bicester man for drug possession after an operation to tackle rural crime in the Kidlington area.
Three other people were given warnings for the same offence.
Ten officers from the Kidlington Neighbourhood Policing Team, including two special constables, carried out the operation between 6pm and midnight on Friday, November 14.
During the night, 40 farms were visited, advice was given to farmers and rural residents and several cars were stopped.
A vehicle was also seized after it was stopped and the driver found to have no insurance.
PC Ian Ledger, who led the operation, said: “Thames Valley Police is fully engaged in tackling rural crime across the region.
“We want to reassure the public that we will continue to carry out these operations in the future.”