The present embodiments provide additive systems for biomass gasification reactors. For example, in one embodiment, a biomass gasification system includes a feedstock preparation system configured to generate a biomass feedstock having a biomass fuel and a tar cracking additive. The system also includes a gasifier configured to receive the biomass feedstock and gasify the biomass fuel in the presence of the tar cracking additive to generate first and second mixtures. The first mixture has producer gas and the second mixture has the tar cracking additive and ash. The biomass gasification system further includes an additive recycle system configured to receive the second mixture and to separate at least a portion of the tar cracking additive from the ash to generate a recycled additive feed for the feedstock preparation system.