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Critical bulk density values

Urban designs succeed only when the tops of trees grow and create shade. This can only happen when roots grow vigorously. Soil bulk density must be below the critical value in order for roots to grow. The chart below shows the bulk density that limits root growth for various soil types. Soil should have a value below that indicated in order to support root growth.

Critical bulk density values for difference soil textures
SOIL TEXTURE Critical bulk density range (g/cc)
clay, silt loam 1.4-1.55
silty clay, silty clay loam, silt 1.4-1.45
clay loam 1.45-1.55
loam 1.45-1.6
sandy clay 1.55-1.65
sandy clay loam 1.55-1.75
sandy loam 1.55-1.75
loamy sand, sand >1.75
Based on Harris 1990 and Morris and Lowery 1988