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.
Brampton
Brampton (population 4,627) is a little market community, civil parish as well as selecting ward within the City of Carlisle area of Cumbria, England, concerning 9 miles (14 km) eastern of Carlisle and 2 miles (3.2 kilometres) south of Hadrian's Wall surface. Historically part of Cumberland, it is located off the A69 road which bypasses it. Brampton railway station, on the Newcastle as well as Carlisle Railway, has to do with a mile outside the community, near the district of Milton. St Martin's Church is renowned as the only church made by the Pre-Raphaelite designer Philip Webb, and also includes among one of the most charming collections of tarnished glass windows created by Sir Edward Burne-Jones, and implemented in the William Morris workshop.