An agricultural harvester may include a system for determining the residue yield of plant materials being ingested by a harvesting implement of the harvester. A controller of the system may be configured to determine the weight of the quantity of plant materials being ingested by a harvesting implement of the harvester based on measurement signals received from the plant yield sensor. The system may be configured to determine the weight of the quantity of crop materials removed from the quantity of harvested plant materials based on measurement signals received from the crop yield sensor. The system may be configured to determine the residue yield value by comparing the determined weight of the quantity of plant materials and the determined weight of the quantity of crop materials.