LiGHTWEiGHT LOAM

Lightweight loam is a mix of Earth and Additives that enhance the thermal properties.
Those additives can be

plant matters (straw, reed, seaweed, cork, hemp etc.)
waste (sawdust, woodshavings, husk of grains, etc.)
mineral products (pumice, foamed glass, expanded clay etc.)

The most common ones are straw, woodshavings and expanded clay.