Cations are held by what on soil clay and organic matter?

Cations are positively charged ions that can be held on soil clay and organic matter through specific locations known as cation exchange sites. These sites are typically found on the surface of clay particles and organic matter due to their negative charges. The negative charges attract and hold onto positively charged cations, allowing for their exchange and movement within the soil. This process is crucial for nutrient availability to plants, as it facilitates the uptake of essential nutrients from the soil.

Cation exchange capacity (the first choice) refers to the total capacity of the soil to hold cations, which encompasses the number of cation exchange sites available, but it does not specifically identify the locations where cations are held. Soil aggregates (the third choice) are clusters of soil particles that may affect water and air movement but do not directly pertain to the retention of individual cations. Soil texture (the fourth choice) describes the size and distribution of soil particles but does not elaborate on the mechanisms of ion exchange. Therefore, identifying cation exchange sites specifically addresses where cations interact with soil components, making it the most accurate answer.