What soil property binds positively charged ions on the surface of soil particles?

What soil property binds positively charged ions on the surface of soil particles?

• A. Cation exchange capacity
• B. Anion exchange capacity
• C. Water holding capacity
• D. Porosity

Answer: (A)

Cation exchange capacity is the soil property that describes how many positively charged ions can be held on the surface of soil particles. Clay minerals and organic matter carry negative charges, creating exchange sites that attract and hold cations such as calcium, magnesium, potassium, and ammonium. Cation exchange capacity quantifies how many of these exchangeable cations the soil can retain and swap with plant roots, which is key for nutrient availability and soil fertility. Soils with higher CEC have more sites to hold nutrients and buffer against nutrient losses. Anion exchange capacity involves binding negatively charged ions, which is a different process. Water holding capacity and porosity relate to moisture and pore space, not specifically to binding cations.

Cation exchange capacity is the soil property that describes how many positively charged ions can be held on the surface of soil particles. Clay minerals and organic matter carry negative charges, creating exchange sites that attract and hold cations such as calcium, magnesium, potassium, and ammonium. Cation exchange capacity quantifies how many of these exchangeable cations the soil can retain and swap with plant roots, which is key for nutrient availability and soil fertility. Soils with higher CEC have more sites to hold nutrients and buffer against nutrient losses. Anion exchange capacity involves binding negatively charged ions, which is a different process. Water holding capacity and porosity relate to moisture and pore space, not specifically to binding cations.