Air pore space is the portion of a soil or potting mix made up of larger pores that remain filled with air after excess water has drained away. These pores supply oxygen to roots and soil microbes and allow carbon dioxide to escape.
In gardening and indoor plant culture, air pore space is a major part of drainage and root health. A mix with too little air pore space stays waterlogged and can lead to root stress or rot, while a mix with more large particles usually holds more air and drains faster. It is closely related to total porosity, but it refers specifically to the air-filled part of the pore system after drainage.
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