Six fire engines and around 40 firefighters were called to a grass fire on Stagg Hill in Enfield.
A hectare of wheat field stubble was alight. One man suffering heat exhaustion and minor burns to his hands was treated on scene and taken to hospital by London Ambulance Service crews.
The Brigade was called at 1447 and the fire was under control by 1610. Fire crews from Enfield, Barnet, Edmonton and Finchley fire stations attended the scene.