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Resource: used or used up in processesClay minerals
Appears in 43 processs and 79 steps. Everything below is linked: open a process to see it in context.
Top processes
- Wetting hydrates the cations between smectite layers: Ca-smectite swells to about 1.9 nm basal spacing, whereas Na-smectite at low salt swells osmotically beyond 4 nm
- COLE = (moist length / dry length) - 1; classes: under 0.03 low, 0.03-0.06 moderate, 0.06-0.09 high, 0.09 or more very high
- Vertisols need at least 30% clay, cracks at least 1 cm wide at 50 cm depth when dry, and slickensides or wedge-shaped peds
- and 4 more in this process
- Soil with 30 percent or more clay dominated by smectite holds water between the layers of expandable clay
- Drying shrinks the matrix: Vertisols have linear extensibility of 6 cm or more in the upper metre
- Wetting swells the clay, closes cracks and cuts infiltration to the slow matrix rate
- and 1 more in this process
Show 37 more processes
- Mineral surface area sets binding sites: smectite about 600-800 m2/g, ferrihydrite 200-700, kaolinite 5-20
- In neutral to alkaline soils exchangeable calcium and clay matter more than clay content alone, while reactive Al and Fe explain most variation in acidic soils
- Saturation: the mineral-bound pool approaches a ceiling set by clay plus silt and reactive metals, so extra inputs accumulate as particulate organic matter or are respired
Living soil system
2 stepsSoil formation
2 stepsOcclusion in aggregates
2 steps- Soil moisture raises the threshold: u*t increases by [1 + 1.21 (w - w')^0.68]^0.5 with w' = 0.0014 (%clay)^2 + 0.17 (%clay), so a 20% clay soil at 8% gravimetric water has about twice the dry threshold
- Impacts of saltating grains break aggregates and eject dust, so vertical dust flux is proportional to saltation flux with a ratio that rises with soil clay content (sandblasting)
Often found with
Clay minerals 37Water 22Soil organic matter 17Smectite 15Carbon 14Iron oxides 13Soil water 11Soil 9Iron oxides 8Calcium 7Pore space 7Mineral surfaces 7
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