What is a Macronutrient?

Macronutrients typically refer to the six major essential nutrients that plants need in large quantities from the soil in order to thrive. There are two groups of macronutrients: Primary and Secondary.

There are three primary macronutrients, which plants use large amounts for growth and survival:

• Nitrogen (N)
• Phosphorus (P)
• Potassium (K)

Potassium and phosphorus macronutrient levels are included in your SoilKit results, along with estimated nitrogen release (ENR) under Soil Properties. Click here to learn why soil tests generally don't measure total nitrogen.

There are three secondary macronutrients, which plants need in more moderate amounts:

• Calcium (Ca)
• Magnesium (Mg)
• Sulfur (S)

SoilKit reports calcium and magnesium levels, while Sulfur is the most common amendment recommendation to balance high pH soils. Similar to nitrogen, sulfur is often found in the soil in the form of negatively charged anions that are highly mobile, so soil levels can fluctuate greatly over shorter lengths of time than other nutrients.

There are three other elements that are sometimes considered as macronutrients since they are essential for plant growth: Carbon (C), Oxygen (O), and Hydrogen (H). However, unlike the soil macronutrients, plants mostly get these elements from air (O2 and CO2) and water (H2O).