What is the main limiting factor for soil surface algae? And for algae living in the soil (up to a depth of 1 cm)?

The limiting factor for algae on the soil surface is water, the surface dries quickly, and for algae life, water is the habitat.
In the soil column, the limiting factor may be the presence of mineral substances, which dissolve, seep into deeper layers and the algae will be doomed to starvation.

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