- increase bulk density, where soil pores are now too small to accommodate the root cap's growth
- increase soil's ability to resist deformation (soil strength), and prevent root penetration.
- crushes natural soil aggregates and associated macropores, thereby preventing adequate water and air flow.
Here are some definitions:
Bulk density: weight per volume of soil
Soil Strength: ability of a soil to resist deformation (change in shape)
Plasticity: ability of a soil to be molded or deformed by pressure
Cohesion: stick/stay together
Soil aggregates: soil particles that are held together in one mass
Macropores: soil pores large enough to allow for air and water flow, and even some small animals (some animals make macropores!)