Tracker, the vehicle recovery expert, said Cambridgeshire and Lincolnshire are hot spots for thieves, who steal up to £70m of agricultural kit a year in the UK.
The latest victim, a drainage company, was lucky when its £60,000 tractor stolen from Wisbech was recovered in Essex.
Organised criminals operate internationally, shifting kit to countries such as Poland, said Stuart Chapman, police liaison officer at Tracker. He said: "Up to an estimated £70m of plant and agricultural machinery is stolen annually and only five per cent is recovered.
"It amazes me that equipment is still made without a unique ignition key, which makes it relatively easy to steal."