Stratified soils are those that are characterized by abrupt porosity changes at various depths within the potential active root zone. These changes in dimensions of the spaces between soil particles affect water and air movement and can limit the depth of the active root zone. In turn, this determines the total amount of soil water available to plant.
Soil stratifications are caused by abrupt texture changes and compaction. The most common textural change in the Coachella Valley is caused by the role of water in soil formation. Flooding and lake silt deposits are the most common cause of stratification here. The cuts and fills made in the process of shaping a country club or HOA on the valley’s finer soils often expose stratifications. The weight of heavy earth moving machinery compresses silty layers resulting in compacted soil stratifications. Shallow stratifications can cause perched water tables and interfere with turf root development. Tree and shrub roots are affected by deeper stratifications as well.
The only way to determine the presence of stratifications on soils is to dig a backhoe pit and examine the soil profile density and texture.