Crews from Pontefract, Hemsworth, South Elmsall and Wakefield continued to dampen the blaze at Old Musgrave Farm, off Main Street, last night.
Crews are still at the farm but say the fire is “on it’s way out.”
More than 30 firefighters and seven pumps were initially called to put out the flames which tore through paper bales and farm machinery yesterday morning.
A 14-year-old boy has been arrested and released on police bail in connection with the incident.
Mark Catney, Det Insp for the Wakefield District said enquiries are ongoing.
He said: “We will need to gain forensic evidence and speak to witnesses.
“A lot of damage has been caused by this fire.”