What is the effect of increasing soil organic matter on CEC?

The correct answer highlights a foundational principle in soil chemistry and fertility management. Increasing soil organic matter directly enhances the cation exchange capacity (CEC) of the soil. CEC refers to the soil's ability to hold and exchange positively charged ions (cations) such as calcium, magnesium, potassium, and sodium, which are crucial for plant growth.

Organic matter contains negatively charged sites that can attract and hold cations. As organic matter content increases, these charged sites provide more capacity for the soil to retain cations. This enhanced retention helps to improve nutrient availability for plants, as well as water retention and soil structure.

Furthermore, organic matter also supports microbial activity, which can further influence nutrient cycling and availability in the soil. Thus, the relationship between organic matter and CEC is a vital concept in nutrient management practices, emphasizing the importance of maintaining or increasing organic matter levels for sustainable soil fertility.