All parts of the plant need oxygen, leaves, stems and roots. In the slab, roots need oxygen for cell respiration. When there is enough oxygen at the roots, the root system can function optimally.
Oxygen is also used by micro organisms, fungi and bacteria. In stonewool mainly bacteria, which are present in large numbers a few hours after wetting up the stonewool. When there are circumstances with low oxygen levels, the micro organisms can compete with the roots for the use of oxygen.
For Oxygen availability
Oxygen supply in the substrate is important for good plant growth. In the practice of growing plants, this means that the water content of the wettest part (bottom layer of substrate) need refreshment and air. When there is 80% water content at the bottom layer of a slab, the air canals make sure that oxygen can get to the water and plant roots (diffusion). At high temperatures (32 oC), less oxygen can solve in water, and roots at the most wet parts of the substrate can have problems with to lower oxygen levels in the irrigation water.
“To control the O2 to realize the potential of the slab.”