Well, the atmosphere only has to be non-toxic to plants, if you are actually using robots to sow, tend, and harvest. CO2/Nitrogen mix perhaps? Compartmentaliza

Well, the atmosphere only has to be non-toxic to plants, if you are actually using robots to sow, tend, and harvest. CO2/Nitrogen mix perhaps? Compartmentalization and lack of toing-and-froing by humans would help too.