What unit is commonly used to measure cation exchange capacity in soil?

Cation exchange capacity (CEC) is a crucial measure of soil fertility, representing the soil's ability to hold and exchange positively charged ions (cations), such as calcium, magnesium, potassium, and sodium. The most commonly used unit for measuring cation exchange capacity is milliequivalents per 100 grams of soil, often simply referred to as milliequivalents (meq). This unit provides an understanding of how many cations the soil can hold, which directly affects nutrient availability for plants.

The significance of using milliequivalents lies in the relationship between the number of valences carried by the cations and the soil's cation exchange sites. Milliequivalents allows for the expression of cation exchange capacity in a consistent and meaningful way across different soil types.

Other options, such as parts per million (PPM), grams per liter (g/L), and kilograms per hectare (kg/ha), measure different aspects such as concentration, weight, or area-based applications. These units do not represent the cation exchange process within the soil structure, making them unsuitable for conveying cation exchange capacity. Therefore, milliequivalents is the most appropriate unit for this measurement, aligning with agronomic practices and