In 1866, he became editor of Geographische Jahrbuch (Geographic Annals, (bd. 1-66, 1866-1983),[1] and from 1872, with Hermann Wagner (1840–1929), edited the geographical/statistical review, Die Bevölkerung der Erde. Starting in 1876, he headed the editorial staff of the statistical section of the Gothaischen Hofkalenders, and in 1878, following the death of Petermann, he became editor of Petermanns Geographischen Mitteilungen.
In 1872, Behm published an article (Beweise für die Identität des Lualaba mit dem Congo), which scientifically demonstrated that the Lualaba was a headstream of the Congo River. This claim was later confirmed as factual by explorer Henry Morton Stanley in 1877.