Which soil component is most associated with high cation exchange capacity?

• A. Bulk density
• B. Water-holding capacity
• C. Cation exchange capacity
• D. Albedo

Answer: (C)

Cation exchange capacity is a measure of how many exchangeable cations a soil can hold on its negatively charged sites, which mainly come from clay minerals and organic matter. Soils with more clay and higher organic matter have more negative charges and thus a higher capacity to hold and exchange nutrient cations like calcium, magnesium, potassium, and ammonium. That direct link between the soil’s ability to exchange cations and the concept being asked makes this option the best fit. The other terms describe different properties: bulk density relates to how compact the soil is, water-holding capacity to moisture retention, and albedo to surface reflectivity.