Soil structure is more important than texture, color or parent material. It is also more important than any fertilizers that can be applied. Good soil structure allows water and air movement, and it provides channels through which roots grow. Overworked, poor soils show a very indistinct soil structure. 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.