Which nutrient is NOT typically associated with cation exchange capacity?

Cation exchange capacity (CEC) is a key property of soil that influences its ability to hold and supply essential nutrients to plants. CEC refers to the ability of soil to retain positively charged ions, known as cations, which include essential nutrients like potassium, calcium, magnesium, and others.

Potassium, calcium, and magnesium are all cations that directly interact with soil particles, specifically clay and organic matter, allowing them to be exchanged with plant roots. They play crucial roles in various physiological processes in plants, including nutrient uptake and enzyme function.

In contrast, nitrogen is most often present in the soil in an anionic form (as nitrate or ammonium ions, for example). Although nitrogen is vital for plant growth, particularly for amino acids and proteins, it does not participate in cation exchange capacity in the way that the other listed nutrients do. This distinction is significant because it highlights the specific roles that different nutrients play in soil chemistry and plant nutrition.

Therefore, nitrogen is not associated with cation exchange capacity, making it the correct choice in this context.