The looseness of soil has a positive impact on a plant 's roots' growth in that soil.
Soil or dirt is typically high in silica and alumina.
The looseness of dirt has a positive impact on  plant's roots' growth in that dirt.
What has a positive impact on root growth in dirt?

  - nutrients
  - burrs
  - exercise
  - support
  - evaporation
  - looseness
  - Sand dollars
  - sun's heat