Assuming the concept of "prussian way" defended by Barrington Moore Jr., this article retakes some important theses on the study of the agrarian systems in Rio de Janeiro, in the context of the crisis of slave labor and transition to free labor in the second half of the 19th century. The main argument of this work is centered upon the failure of the Land Law of 1850 in creating an effective closed agricultural frontier. Henceforth, we support that the pressure exerted by de facto free lands is crucial to the nature of labor relations after 1888. The conclusions of the studied theses, when analyzed as a whole, enables us to affirm that the existence of free lands wielded hard pressure against proletarization mechanisms acting over rural workers, and so leading to the use of "repressive labor systems" as a viable alternative to the survival of the large estate, revealing itself as a fundamental aspect of the conservative modernization, as conceived by Moore Jr.
prussian way; conservative modernization; slave labor; agrarian systems; agrarian question.