“Macronutrients” versus “micronutrients”?

Question: What’s the difference between a macronutrient and a micronutrient fertilizer?

bananas

Just like people require different amounts of different nutrients for good health–such as the potassium supplied by bananas–plants need different quantities of “macro-” and “micro-nutrients.” But all are important. Photo by: Mas NurWalin (www.flickr.com)

Answer: “Macro” and “micro” nutrient fertilizers refer to the quantity of nutrient needed by plants, not to their importance to plant growth. The following statements define the categories more specifically:

Macronutrients are divided into two classes: primary and secondary. The three primary macronutrients are nitrogen (N), phosphorus (P), and potassium (K); all are required in relatively large quantities by plants.

The secondary macronutrients, calcium (Ca), magnesium (Mg), and sulfur (S), are required in lesser quantities relative to the primary category.

Micronutrients are required by plants in far smaller quantities than any macronutrient. Micronutrients required by plants include zinc (Zn), iron (Fe), manganese (Mn), copper (Cu), boron (B), molybdenum (Mo), and chlorine (Cl). Relative to the macronutrients, micronutrients are required in trace quantities.

Remember that the words “primary” and “secondary” relate to the quantity needed, and not their importance to plant growth; all are equally important.

–Answered by Gary “Pete” Peterson, Colorado State University

Have a question for Soils Matter? Post it as a comment below, or email us at soils-matter@soils.org

 

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