The Soil Depth property measures the vertical distance from the soil surface to an impenetrable layer, such as bedrock or a hardpan. Soil depth is a crucial factor influencing root development, water storage, and plant growth. Shallow soils may limit root growth, while deep soils can support more extensive root systems. Source: Brady, N. C., & Weil, R. R. (2008). The Nature and Properties of Soils (14th ed.). Pearson Prentice Hall.