Which soil property is a measure of the soil's ability to hold and exchange cations, influencing nutrient availability and buffering?

• A. Cation Exchange Capacity (CEC)
• B. Soil texture
• C. Soil moisture
• D. Soil pH

Answer: (A)

Cation Exchange Capacity is the measure of a soil's ability to hold and exchange cations, which directly influences nutrient availability and buffering. It represents the total negative charge on soil particles (mainly clay minerals and organic matter) that can attract and hold positively charged nutrient ions such as calcium, magnesium, potassium, and ammonium. This capacity controls how many nutrients the soil can retain in the root zone and how easily they can be exchanged with plant roots as needed. A higher CEC means more exchange sites, greater nutrient-holding ability, and stronger buffering against pH changes, helping maintain stable nutrient availability and reducing leaching of cations. CEC is typically expressed in cmolc per kilogram of soil. While texture, organic matter, and moisture influence nutrient dynamics, CEC specifically measures the soil’s capacity to hold and exchange cations.