What is required for a sandy mollic horizon thickness?

A sandy mollic horizon is a specific type of soil layer that exhibits characteristics associated with moisture retention, organic matter content, and structure, typical of mollic horizons while being composed primarily of sandy textures. The requirement for a sandy mollic horizon is that it must be at least 25 cm thick. This thickness is important because it allows the horizon to effectively store moisture and maintain the fertility advantages associated with mollic characteristics. A thickness of at least 25 cm ensures that the horizon can support plant growth and provide essential nutrients. Therefore, the requirement aligns with soil classification standards that emphasize both the physical properties and ecological functions of the mollic horizon, particularly in sandy soils where water retention may be more challenging due to the larger particle size.