According to Official Guinness Records,
The greatest area ploughed in 24 hours with a six-furrow plough to a depth of 25 cm (9.75 in) is 91.37ha 225.7 acres. This was achieved by Matthias Robrahn of Pogeez, Germany, in a John Deere Type 4955 (228 PS) on 23-24 Sep 1992.
For a complete list of Unknown date records, please visit Unknown date Guinness Records in Germany.