Buried Roman fermentation jars (dolia) from Villa Regina, Boscoreale.Credit: E. Dodd, courtesy of the Ministero della Cultura – Parco Archaeologico di Pompei
It sure seems like a clumsy way to ferment wine, especially if you add the grapes to the containers.
Seems like it would be hard to empty and clean between batches...to reach in and scoop it all out and rinse them. I guess some residual would remain to act as a starter to the process.