If the plant material to support each person is drawing down 2 moles CO2 per hour (doubled from earlier calculations, because not all the carbon ends up in edib

If the plant material to support each person is drawing down 2 moles CO2 per hour (doubled from earlier calculations, because not all the carbon ends up in edible parts), then a tonne of carbon should supply the plants needed for 5 people for a year. By the end of the year, you've probably closed the loop, so the fixed carbon is returning to the air.