From the last post, SoilMoist is a soil conditioning polymer that improves the water retention of soil. When exposed to water, SoilMoist swells into a gel-like substance.

The Chemical composition of SoilMoist is cross-linked polyacrylamide

^Chemical structure of poly acrylamide.

Cross-linked polyacrylamide is highly hydrophilic, it can H-bond with water, which explains it’s usefulness as a water retention agent in soil.

Concerns have been raised that polyacrylamide used in agriculture may contaminate food with acrylamide, a known neurotoxin. While polyacrylamide itself is relatively non-toxic, it is known that commercially available polyacrylamide contains minute residual amounts of acrylamide remaining from its production, usually less than 0.05% w/w.

Information found on Wikipedia: