The primary mode of soil aeration

Solution

Mass flow refers to the movement of gases (such as oxygen and carbon dioxide) through the soil in response to pressure gradients. In the context of soil aeration, mass flow is a significant mechanism by which gases, especially oxygen, move through the soil pores due to differences in partial pressures. This movement occurs along with the movement of water in the soil, influencing the availability of oxygen to plant roots and soil microorganisms.