Trace elements, partially because of just how little the plants metabolize, are a little tricky to keep track of. Generally, if you’re using compost or manure or rotating your plants, these elements will never be in short supply. That being said, it’s nice to know what’s out there and what these nutrients do for the plant.
Calcium, Magnesium, and Sulfur. Secondary only refers to the quantity, not the importance of the nutrients. These are just as important as NPK!
Part 1 of 4. Plants want to gobble up everything they can of 3 key macronutrients - Nitrogen, Phosphorus, and Potassium. Here's what NPK does to plants!