What does soil compaction reduce?

• A. Root penetration, oxygen availability, and infiltration
• B. Soil elasticity
• C. Water retention capacity only
• D. Microbial diversity

Answer: (A)

Soil compaction squeezes the pore spaces in the soil, especially the larger macropores that air and water move through. When these pores are crushed, the soil becomes denser (higher bulk density) and roots have a harder time penetrating, oxygen can’t diffuse as readily to the roots, and water infiltration into the soil slows or stops, leading to surface runoff or ponding. These combined effects—less room for roots, reduced oxygen around roots, and lower infiltration—best capture what compaction reduces. Other options aren’t as direct: elasticity isn’t the main change; water retention can vary and isn’t universally reduced; microbial diversity can be affected but isn’t the primary, consistent consequence in the same clear trio.