Which of the following are considered dominant cations in California soils?

The dominant cations in California soils are primarily calcium (Ca), magnesium (Mg), potassium (K), and sodium (Na). Each of these cations plays a critical role in soil chemistry and plant nutrition.

Calcium is essential for cell wall structure and stability in plants and aids in nutrient transport. It is the most abundant cation found in many soils, particularly in Californian agricultural regions. Magnesium is vital for photosynthesis as it forms the central atom in the chlorophyll molecule. Additionally, it serves as a cofactor in various enzyme systems within the plant. Potassium is crucial for water regulation, enzyme activation, and overall plant vigor, while sodium can also contribute to soil structure and water retention in certain contexts, even though it is typically present in lower amounts compared to the other cations mentioned.

The other choices do not accurately represent the dominant cations in California soils. For instance, aluminum and iron, while present, are not typically classified as dominant cations in the context of soil fertility impacting plant growth. Sodium chloride, found in one of the other options, is not a cation typically associated with enhanced soil fertility. Phosphorus and sulfur, included in another choice, are not cations and thus do not fit the criteria