As N₂O emissions were present in preindustrial times, only the difference between current and preindustrial emissions represents net human-induced climate change. Large uncertainty exists in previous estimates of preindustrial N₂O emissions from the land biosphere. Our estimate using process-based model was the first study that provided the preindustrial N₂O emission at the biome, sector or country, and global level, which could be a useful reference for future climate mitigation.