FORESTRY UPDATE by Gary Allen Burns 11-9

By Gary Allen Burns, consulting forester

Soils can be grouped into textural classes based on the proportions of sand, silt, and clay in the soil. The texture influences water availability, plant uptake of mineral ions, and gas exchange (O2 and CO2) between the soil and atmosphere (aeration). Sand has mineral particles that range from 0.02 to 2.00 mm in diameter and sandy soil has more than 90% of these large particles. These coarse-textured soils drain more rapidly and may tend to droughtiness.

Clay has mineral particles that are less than 0.002 mm in diameter. These fine-textured soils tend to be sticky when wet, but they absorb moisture more slowly than other soil textures. Clay soil has more than 60-100 percent of its mineral particles being less than 0.002 mm in diameter.

Silt mineral particles range in size from 0.02 to 0.002 mm in diameter, midway between sand and clay. They are also midway in water holding properties. Loams have equal proportions of sand, silt, and clay.