Tasteless, colorless, odorless, element – cannabis plant roots need oxygen in the soil in order to grow.
Merriam-Webster Online Dictionary
oxygen (noun)1.
a reactive element that is found in water, in most rocks and minerals, in numerous organic compounds, and as a colorless tasteless odorless diatomic gas constituting 21 percent of the atmosphere, that is capable of combining with all elements except the inert gases, that is active in physiological processes, and that is involved especially in combustion - see element table
2.
something that sustains or fuels - disagreement is the true oxygen of these magazines Joseph Epstein
Air, O2, life-supporting gas, vital element, diatomic molecule