Which of the following is a method for routine additions of cations to the soil?

Fertilization is a method for routine additions of cations to the soil because it involves the application of various fertilizers that contain essential nutrients, including cations such as potassium, calcium, and magnesium. These nutrients are vital for plant growth and play crucial roles in plant metabolism, enzyme function, and cellular structure. By regularly applying fertilizers, growers can ensure that the soil has an adequate supply of these cations, thereby enhancing soil fertility and promoting healthy plant development.

In contrast, planting cover crops primarily serves purposes such as soil protection, erosion control, and improving soil organic matter rather than directly adding cations to the soil. Mulching is mainly used to conserve soil moisture, regulate temperature, suppress weed growth, and prevent erosion, rather than to supply nutrients directly. While weed control is important for maintaining plant health and maximizing crop yield, it does not contribute to soil nutrient levels in the way that fertilization does. Therefore, fertilization is the correct choice for routine cation additions to the soil.