Soils and layers

Calcined clay

Hard-fired clay grit that holds water inside each grain and never packs down.

What the simulation uses

Holds water: 35 % by volume; Water it keeps after draining; the rest runs down to the drainage.
Pore space: 72.5 % by volume; Room for air and water between grains; low means roots suffocate when wet.
Weight: 600 g/L; How heavy a litre is.
pH: 6 to 7 pH; How acid it keeps the soil.
Mould risk: none; How much fresh food it gives white mould; high-risk soils fuzz over in the first weeks.
Nutrients: none; Plant food it brings.
Presses down to: 72 % of its loose depth; How far pressing can pack it, keeping its weight.

Small fired granules that stay near neutral and carry no nutrients. Add them to a mix for lasting air pockets without drying it out.

Also called Turface, fired clay granules.

Estimated, where sources were thin: values estimated from hobby and horticultural references; not measured.