All of us who grow something in the soil—gardeners, homesteaders, and farmers—should be familiar with cation exchange capacity (CEC). It affects plant growth and vigor, the nutrient density of crops, and even disease resistance. Let’s take a peek behind the curtain.
What Is a Cation, and Why Would We Want to Exchange It?
We know our plants need nutrients to grow, flower, and fruit. Some of these nutrients are called “macronutrients” because plants need them in higher quantities. Nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sulfur (S) are commonly classed as macronutrients. Plants also need other nutrients in lesser amounts for proper growth and function. We call those nutrients “micronutrients,” and examples include zinc, iron, boron, manganese, and copper. You’re on the right track if these remind you of the periodic table.
Air and water are the ingredients for photosynthesis, but plants’ complex proteins, enzymes, and carbohydrates require a soup of macro and micronutrients. Those nutrients, many of which are present as ions, come from the
