"Gaseous exchange in plants is performed through tiny holes in the lower (usually) face of the leaf that open and close at appropriate times of the day. Carbon Dioxide is taken in for photosynthesis. Roots absorb water and mineral ions necessary for plant growth. Marijuana likes a small amount of air to reach its roots. This can be achieved by mixing a small amount of sand, polystyrene, permiculite or whatever, to stop the soil from compacting down.
You would be much better off feeding your plants leaves with CO2 and fertilising your plants roots than the other way around. The exact same way that nature treats plants!"
found this on another website, i hope it helps. if this is incorrect i appologize but it does make sense. alright peace