Dương Đình Phương, who was working his garden in Việt Trung Farming Town, and the driver of an excavator, found a bomb lying a depth of over 2m.
He stopped his work and informed local authorities.
The Military Command on Tuesday successfully defused the bomb and removed it.
The bomb, leftover from the war, was a general-purpose M82 series munition reportedly made in the United States, with a length of 1.54m.
Earlier in October, a 226kg bomb left over from the American War in Bố Trạch District was also disposed of by the provincial Military Command.
The MK-82-500LBS bomb was found by local residents while they were searching for scrap in Việt Trung Farming Town.