An Etymological Dictionary of the German Language/brach

by Friedrich Kluge

brach, adj. (espec. in compounds such as Brachfeld, &c.), ‘uncultivated, fallow,’ merely ModHG. In MidHG. there is only the compound brâchkmânôt, ‘June,’ which contains a subst. brâche, f., OHG. brâhha (MidLG. brâke), ‘aratio prima,’ as its first component; Brache is ‘turning up the soil after harvest’; from brechen.