A farm building at a nursery in Spalding was destroyed by fire on Saturday afternoon.
The 30m x 10m barn at Groom Bros in Pecks Drove West was used for storing cardboard boxes and waste peat.
Opperman Plants, of Low Fulney, rents the site from Holbeach firm Ashley King Developments.
Business owner Mike Opperman raised the alarm at about 3.15pm on Saturday, after spotting the blaze while driving on the A16 bypass.
He said: “I don’t think the fire had been going very long when I arrived.”
Two fire crews from Spalding were supported by another from Donington. Damping down continued until Sunday morning.
The cause was said to be a nearby bonfire.
The remote site has been “nothing but a problem” to Mr Opperman. Last year a fuel lorry was used to steal 15,000 litres of gas oil and a couple of months ago he alerted police to a stash of stolen property.
There has also been evidence of rough sleepers and drug-taking on site.
