What is the mechanism through which water moves from the mat into the root substrate in mat irrigation?

In mat irrigation, water moves from the mat into the root substrate primarily through capillary action. Capillary action refers to the ability of water to move within the small spaces of a porous material, such as soil or a growing medium, due to adhesive and cohesive forces. When the mat is saturated with water, the moisture is drawn into the root substrate through these tiny pores, allowing the roots of the plants to absorb the necessary water.

This process is effective in providing an even and consistent moisture level in the growing medium, making it ideal for many types of plants in greenhouse or nursery settings. The small pores in the substrate facilitate this water movement, further enhancing root access to moisture.

Other mechanisms, such as gravity, mainly influence downward water movement in macroscopic quantities rather than the fine capillary flow seen in mat irrigation. While evaporation can affect moisture levels at the surface, it does not directly facilitate the movement of water from the mat to the roots. Filtration relates more to the process of separating particles from liquids and is not applicable in the context of how water moves into the root substrate.