In plant nutrition, three groups of mineral elements used in fertilization are defined: macronutrients, secondary elements, and microelements, also called trace elements.
Here, we will focus on the first group—macronutrients—reserving secondary elements and trace elements for future articles.
The group of macronutrients for plant nutrition.
The macronutrient group for plants consists of three essential mineral elements that plants need in large quantities for optimal growth and development: nitrogen, phosphorus, and potassium, represented by their chemical symbols N-P-K.
These three elements are typically listed first on fertilizer labels, often represented by their relative abundances in the formulation. For example, in JISA’s mineral fertilizer formulations, products such as Jisafol® 25-5-15, CristalJisa® 13-40-13 or Jisafol® 11-6-36 specify the levels of each of these nutrients.
Nitrogen, phosphorus and potassium.
Nitrogen (N) promotes vegetative growth and gives plants their green color. It can be considered the driving force behind plant growth and is absorbed by roots from the soil in the form of nitrate (NO3–) or ammonium (NH4+).
In plants, nitrogen combines with compounds from carbohydrate metabolism to form amino acids and proteins. As an essential component of proteins, it plays a role in all major developmental processes and contributes to yield. It’s also important to note that a good supply of nitrogen enhances the absorption of other nutrients.
Phosphorus (P) actively supports root system development and is involved in various cellular biochemical processes. It is absorbed by roots in the form of phosphate ions (H₂PO₄⁻ and HPO₄²⁻).
Phosphorus is vital for energy transfer (ATP), photosynthesis, respiration, root and flower growth, and the formation of DNA and RNA.
Potassium (K) is crucial for enzyme activation, photosynthesis, protein and carbohydrate synthesis, and cellular water balance. It is absorbed by roots as the potassium ion (K+) and supports vegetative growth, fruit development, ripening, and quality.
Additionally, potassium regulates the opening and closing of stomata, which influences cell turgor and helps improve disease resistance and water stress tolerance.
As mentioned, nitrogen, phosphorus, and potassium are the nutrients that plants require in the largest amounts. Thus, when their soil levels drop below what’s necessary for healthy growth, these nutrients must be replenished. This principle aligns with Liebig’s Law, formulated by German chemist Justus von Liebig, which states that plant growth is limited by the most deficient nutrient.