A carriagway of the A421 Buckingham bypass has been closed at Tingewick to assist a clean-up operation, after a lorry spilled its load this afternoon.
Fire, police and ambulance services were called at about 2pm after a lorry turned on its side on the bypass, spilling about 50 litres of diesel and 27 tonnes of chicken feed down a bank.
The lorry, from Noble Foods, in Tring, was at the Tingewick roundabout heading towards Buckingham when it overturned.
A fire crew from Buckingham attended the scene but the driver had been released before they arrived.
The injured man was taken by ambulance to Milton Keynes Hospital.
The Environment Agency also attended the scene.