Hello Cal
"Viertelhüfner" means "owner of a Viertelhufe".
"Hufe" was a certain area of land a farmer was allowed to possess. The owner of a Hufe was a Hüfner, "Viertel" means "quarter". Besides this, with more land, there were "Halbhüfner" and even "Hüfner". Regionally different, another terms but same meaning were "Anspänner", "Halbspänner" and "Viertelspänner" or "Pferdner", "Halbpferdner" and "Viertelpferdner". All together these were farmers who were allowed to have horses. Those terms not only described the economical but also the social status of a member of the local community in a village.
Best regards
Jürgen