Which property of soil is most directly enhanced by high organic matter content?

• A. Subsurface hardness.
• B. Water-holding capacity and aggregate stability.
• C. Cation exchange capacity is reduced.
• D. Air pollution absorption.

Answer: (B)

High organic matter content directly enhances water-holding capacity and aggregate stability. Humus and other organic components are made up of hydrophilic groups that can retain water, so the soil can hold more moisture between rains and support plant needs. At the same time, organic matter acts like a cement that binds mineral particles into stable aggregates, creating a more porous, well-structured soil that maintains good drainage while reducing crusting and erosion. As a result, the soil stays between being too loose and too compact, supporting root growth and moisture retention. In contrast, organic matter actually increases cation exchange capacity, not reduces it, and while soils can absorb pollutants, that’s not the direct, primary change most tied to high organic matter.