The super-absorbent polymers contained in TreeGrow can absorb ~400 times their own weight in water. They are manufactured in Germany and imported by Bioscience. They also attract plant-beneficial microbes which has been shown in peer-reviewed scientific publications. This is likely caused by their high cationic exchange capacity which attracts microorganisms similar to a plant root. These polymers are 100% biodegradable and non-toxic.
Spongolite is a unique mineral of fossilised sponges. Porous in nature, it also holds water but more importantly, it binds anions such as nitrate and phosphate which are retained in the root zone of the growing sapling that can access it.