Yes, your shed does need a base. This is to give it a solid, level foundation. Open soil will not help with the longevity of the shed itself or the contents within. The best materials to use to make your shed base are concrete, natural stone or wood.
Winscombe
Winscombe is a huge village in North Somerset, England, near to the settlements of Axbridge and Cheddar, on the western edge of the Mendip Hills, 7 miles (11 kilometres) southeast of Weston-super-Mare and 14 miles (23 kilometres) southwest of Bristol. The Parish of Winscombe as well as Sandford, centred on the Parish Church of Church of St James the Great, consists of the villages/hamlets of Barton, Hale, Oakridge, Nye, Sidcot and also Woodborough. Historically part of Somerset, Winscombe has a few shops and businesses concentrated in the centre of the town, along Woodborough Road and Sandford Road. There is a doctor's surgical treatment in the town, a vet and also 2 dental experts. West of the town is the Max Bog biological Site of Special Scientific Interest.