Nutrient Roles in Plants

Nutrient Deficient Tomatoes to show nutrient roles in plants

Nutrient Roles in Plants

Nutrient Roles in Plants

October 07, 2021

So you’re constantly dosing your system with extra nutrients and hoping they will help your plants thrive. But in order to manage and maintain the full spectrum of nutrients required in aquaponics, it is important to understand nutrient roles in plants.

Firstly, let’s unpack the nutrients into macronutrients and micronutrients. The difference between these two is only in the amounts required for plant survival.  Macronutrients are required in large amounts whereas, micronutrients are required in smaller quantities.



Carbon (C) Boron (B)
Hydrogen (H) Chlorine (Cl)
Oxygen (O) Copper (Cu)
Nitrogen (N) Iron (Fe)
Phosphorous (P) Manganese (Mn)
Potassium (K) Zinc (Zn)
Calcium (Ca) Molybdenum (Mo)
Magnesium (Mg) Nickel (Ni)
Sulfur (S)  
Brightly Coloured Carrots, Strawberry broccoli and tomatoes that are nutrient packed.

Macronutrient Roles in Plant Nutrition

Carbon, Hydrogen and Oxygen

These are the basic building blocks of the plant and they make up 96% of the mass. Moreover, they are not minerals and they play an important role in the structural components of the plants.


Nitrogen is the backbone of amino acids which are the building blocks of proteins. As you already know, we obtain this nutrient naturally in an aquaponics system through the nitrogen cycle.


This macronutrient is essential for optimal growth in a plant. Therefore a lack thereof can cause stunted growth.


Potassium is a regulating chemical and it plays a key role in the movement of water in and out of plant cells.


 A key structural component of cells walls, calcium is used to transport other substances across the cell membranes.


Without this macronutrient, photosynthesis is unable to take place due to the inability to synthesize chlorophyll.  Then the plant cannot produce its own food because photosynthesis is not taking place.


This macronutrient is made up of two important amino acids. Which aid in both protein production and photosynthesis. It is also an important component of vitamins, proteins and coenzymes.

Micronutrient Roles in Plant Nutrition


This micronutrient contributes to the structural integrity of the cell wall. And additionally plays an important role in balancing the amounts of sugar and starch in a plant.


Of all the micronutrients, Iron is required by plants in the largest amounts. Moreover, Iron is an important electron carrier and is crucial for the production of chlorophyll for photosynthesis.


Copper assists in carrying out reactions that occur in both photosynthesis and respiration.


Zinc is an activator of enzymes that are involved in the production of growth hormones.


Manganese plays a critical role in photosynthesis as it is used to free oxygen.


This micronutrient plays a key role in potassium absorption as well as assists in the nitrogen cycle within a plant.


Chlorine has a role in the oxygen-evolving reactions of photosynthesis. It also assists in the operation of the stomata which is necessary for gas regulation in a plant.


Nickel has a very important role in an aquaponics system as the fish produce high levels of urea. It is a component of an enzyme called urease. Urease is crucial in the nitrogen mobilization process. In summary, it ensures that there is no build-up of urea in the plant as this can become toxic.

As you can see from above, that even though they all have different jobs and different dosing requirements, each nutrient has a specific role to carry out in plant nutrition. As a farmer, you need to make sure you understand the nutrient roles in plants. Additionally, if you think you are experiencing a nutrient deficiency in your system make sure to check out our blog post on Common Plant Deficiencies to see how you can spot and treat your problem in a safe, natural way.

Mulders Chart

Antagonism: High levels of a particular nutrient in the soil can interfere with the availability and uptake of other nutrients. For example, high nitrogen levels can reduce the availability of boron, potash and copper; high phosphate levels can influence the uptake of iron, calcium, potash, copper and zinc; high potash levels can reduce the availability of magnesium. Thus, the application of high levels of nitrogen, phosphorus and potassium can induce plant deficiencies of other essential elements.

Stimulation: This occurs when the high level of a particular nutrient increases the demand by the plant for another nutrient. For example, increased nitrogen levels create a demand for more magnesium.