Which clay type is primarily associated with Anion Exchange Capacity (AEC)?

The correct choice regarding the clay type primarily associated with Anion Exchange Capacity (AEC) is iron oxide clays. Iron oxide clays are significant in soil science because they have the ability to adsorb and release anions due to their surface properties. This characteristic is crucial for nutrient management since it indicates how well the soil can hold onto essential nutrients that negatively charged ions might represent, such as nitrate and phosphate.

Iron oxides contribute to the overall charge balance in soils and enhance the retention of anions compared to pure clay minerals that predominantly feature cation exchange capacity without significant anionic activity. This property makes iron oxide clays particularly valuable in nutrient management practices, especially in assessing soil fertility and potential nutrient availability.

In contrast, other clay types, such as kaolinite, generally have lower AEC due to their structure and limited capacity for ion exchange, which is primarily cationic. Ionic clay does not directly refer to a specific type of clay recognized in soil science, making it less relevant. Montmorillonite, while important for its high cation exchange capacity, does not typically feature significant AEC compared to iron oxide clays. Thus, understanding the unique attributes of iron oxide clays in terms of anion exchange is essential for nutrient