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.
Blandford Forum
Blandford Forum, typically Blandford, is a market community in the North Dorset area of Dorset, England, sited by the River Stour concerning 13 mi (21 km) northwest of Poole. It was the management headquarters of North Dorset District Council till April 2019, when district councils merged to become Dorset County Council. Blandford is remarkable for its Georgian style, the result of reconstructing after the majority of the community was damaged by a fire in 1731. The restoring work was assisted by an Act of Parliament and also a donation by George II, as well as the rebuilt town centre-- to designs by neighborhood architects John as well as William Bastard-- has made it through to the present day largely undamaged. Blandford Camp, an army base, is sited on the hills 2 miles to the north east of the town. It is the base of the Royal Corps of Signals, the communications wing of the British Army, as well as the website of the Royal Signals Museum. Dorset County Council approximates that in 2013 the town's civil parish had a population of 10,610. The town's economic climate is based upon a mix of the solution field and also light market, as well as supplies employment for regarding 4,000 individuals.