The ammunition remains in the ground after a military training area was closed, which means firefighters must keep a distance of 1,000 meters from the flames.
The rescue service cannot actively fight the fire, that is the problem, district spokesman Marten Schröder told AFP.
The safety distance also applies from the air, which means that the fire cannot be fought by helicopter, as it would then have to fly so high that the water would be blown away by the wind rather than hitting the target.
According to local authorities, the flames have consumed about 150 hectares. Around 200 people are working to extinguish it.
