In Indonesia, agricultural rituals are consistently performed before, after, and even during specific periods, with variations in form across regions and ethnicities. We outline the results of our study of the siungkapungkapon ritual and its role in agricultural practices of the Batak Toba community. We examine the ecological context and archaeological data relevant to rice farming. Our study includes interviews with community members and observation of rites involving the siungkap-ungkapon stone. We discuss intertwined aspects of the rite—religious, social, ecological, and technological. The rite itself has been practiced at least since the Late Neolithic with a view to receive the ancestors’ blessings and instructions as to which rice variety should be cultivated during a specific season. The ritual reveals the peasants’ knowledge of agricultural practices, rice types, and the environment, all of which, taken together, ensure the highest yield. How the choice of the rice variety depends on the presence of ants under the stone is not immediately apparent. We conclude that the siungkap-ungkapon ritual, which involves practical knowledge, strengthens social unity and is supposed to optimize agricultural labor.