Caliche Many southern Arizona soils have layers of caliche either on or under the surface. Layers will vary in thickness from a few inches to several feet, and there may be more than one caliche layer in the soil.
Caliche causes three problems in the yard or garden.
The caliche layer can be so tight that roots cannot penetrate through it. The result is that plants have only the soil above the caliche to use as a source of nutrients and water and normal root development is restricted. The same conditions that restrict root penetration also reduce water movement. Water applied to the soil cannot move through the profile if a restrictive caliche layer is present. The restricted water penetration can contribute to problems arising from inadequate root aeration and can lead to accumulations of salt in the soil surface.