Aggregates do not exist, so there are few air spaces between particles. Roots can suffocate and die where large amounts of water have forced air out of the space. Soil with good tilth allows seedlings to emerge easily. It allows roots to penetrate soil. Soil with good tilth has good structure.
Organic matter attracts earthworms that drill channels deep into the subsoil.
These channels provide needed space for plant roots, air and water. In addition to earthworms, microbes live in soil. Microbes break some nutrients and organic matter into simpler units that plants can use. The organic remains of microbes improve soil structure. These microbes depend on plant roots to provide them with food.