The MK82 bomb is 1.67m in length and 29cm in diameter. It contains 87 kg of explosive substance, with detonation diameter spanning 600 metres.
Three shells were also found in the same area with the bomb by local farmers who dug holes to plant pepper trees.
Dak Nong is located in the south of the Central Highlands and houses the key road connecting the region with the southeast region. Once a warzone, the province has been tackling unexploded bombs for many years.
During the war, the US army dropped more bombs on Vietnam than were deployed in the First and Second World Wars combined, according to the US organisation Clear Path International.
It is estimated that about 30% of the bombs remain unexploded.