Understanding Caliche

Caliche is a term associated with desert soils and refers to a layer of cemented soil or hard tray. It is a deposit of lime that binds sand and gravel so strongly and firmly that roots and water do not pass. Caliche can be a layer of gray or light brown soil or clumps of soil. If you are not sure if it really is caliche, sprinkle in a few drops of vinegar or acid. Caliche layers are fizzy or bubbly vigorously. Caliche can be on the surface, close to it, or even far below the surface. And it can be from a few inches to many feet thick. Caliche can also exist as pebbles or small rocks known as popcorn caliche.

A major plant problem in relation to caliche is its obstacle to root penetration. Even if the layer is loosened, the roots may not yet penetrate. A second problem is drainage. The soil must be allowed to drain to ensure adequate levels of oxygen and gas exchange for root growth. Caliche layers do not allow water to drain into deeper soil. Yellowing of the leaves or chlorosis may be observed if the root zone does not have enough oxygen due to poor drainage.

The only way to solve a caliche problem is to remove it, create drainage holes through the layers, or plant shallow-rooted plants that can tolerate shallow waterings like annuals or grasses. Just because you have caliche present in your yard or garden doesn’t mean you can’t plant anything. It means you need to recognize the challenges and make plant selections that can tolerate these soil conditions. Happy gardening!