Substrate handling influences air porosity of substrates

A substrate has four functions: it provides support for roots, it serves as a water reservoir, it serves as exchange sites for nutrients and it promotes the gaseous exchange between the rhizosphere around the roots and the atmosphere.

There are many factors that influence the air porosity of a substrate, such as how the substrate is handled and the depth of the container. But other factors, such as the time of year and temperature of the substrate solution influence the amount of air/oxygen plant roots need.

It is best to use a growing medium that offers the ideal air porosity for your watering technique as well as the requirements of the crop.

When using a bale breaker to fluff compressed substrate, it is necessary to minimize the time of mixing, add enough water to have the ideal water content for transplant or sowing and use the machine with slow turning ribbons or paddles.

The excessive fluffing or mixing destroys peat fibers and aggregates creating fine particles, which reduces air porosity and drainage and the medium dries out slowly.

Read more at PRO-MIX (Jose Chen Lopez)