Higher CEC indicates more exchange sites available for holding nutrients; which type of nutrients are held on exchange sites?

• A. Cations
• B. Anions
• C. Water molecules
• D. Gases

Answer: (A)

The key idea is that the exchange sites on soil particles are negatively charged, so they attract and hold positively charged nutrient ions. Higher CEC means more of these sites are available, acting as a reservoir for cations such as calcium, magnesium, potassium, ammonium, and sodium. These exchangeable cations can be released into the soil solution when plants need them or when other cations displace them, helping with nutrient availability and reducing leaching. Anions, water molecules, and gases aren’t held on these negative exchange sites in the same way, so the nutrient types stored here are specifically cations.