5.1.19 (HL)—Sand, silt, clay differences

Clay particles are much smaller than silt and sand and generally provide more charged surface for cation exchange than quartz-rich sand.

Higher CEC means greater ability to retain positively charged nutrients such as K⁺, Ca²⁺ and NH₄⁺. Humus can also raise CEC, so texture is not the only control.

A clay-humus soil can retain ammonium after rain, while coarse quartz sand is more likely to leach it.

Smaller particles provide more reactive charged surface per mass; confirm mineralogy and organic matter.

High CEC does not guarantee good drainage or fertility; retention and availability are different.