What is the Cation Exchange Capacity (CEC) of soil?

Cation Exchange Capacity (CEC) refers to the soil's ability to hold and exchange positively charged ions, known as cations, which include essential nutrients like calcium, magnesium, potassium, and sodium. This property is crucial for plant health, as it directly influences the availability of these nutrients to plant roots.

The reason that the ability to retain cations and supply them to roots is the correct answer is that CEC essentially measures how well soil can retain these vital nutrients, and subsequently, how readily it can supply them to plants for uptake. A higher CEC indicates a greater capacity for nutrient retention, which can enhance soil fertility and improve plant growth.

Understanding CEC helps highlight the important role of soil composition and structure in agriculture and ecology. This capacity is influenced by factors such as soil texture, organic matter content, and pH, all contributing to the soil's overall health and productivity. Thus, recognizing the concept of CEC is vital for effective soil management and gardening practices.