Cation saturation and soil fertility are connected through which concept?

• A. Cation saturation measures soil moisture content.
• B. Cation saturation is described as the percentage of exchange sites occupied by specific cations.
• C. Cation saturation indicates total organic matter.
• D. Cation saturation is the sunshine hours in a field.

Answer: (B)

Understanding how nutrients are held in soil helps explain fertility. Cation saturation refers to the percentage of exchange sites on clay minerals and organic matter that are occupied by specific cations (like calcium, magnesium, potassium, and sodium). Since plants take up nutrients from these exchange sites, the balance of cations directly affects nutrient availability, pH buffering, and soil structure—key aspects of fertility. So describing cation saturation as the proportion of exchange sites occupied by particular cations best captures its relationship to soil fertility. Other statements describe soil moisture, total organic matter, or weather factors like sunshine, which are not what cation saturation measures.