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How substrate structure influences air porosityRoots need oxygen for respiration. The amount of air required in the substrate is going to depend mostly on its total porosity. Total porosity is the percentage of the total volume of substrate that it is not occupied by solids and is composed of both air and water.
Air porosity is the percentage of air contained in a fixed volume of substrate after the substrate is saturated with water and the free water has drained. The higher the air porosity, the more oxygen the roots can acquire.
It is important to mention that some substrate components, like perlite, have closed pores. Therefore, even when the substrate is completely saturated, there are trapped air pockets within the component that cannot be used by the roots.
Read more at PRO-MIX (Jose Chen Lopez)
Publication date: 11/27/2017
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