Unlocking the value of micronutrients

For arable growers, there has long been a focus on the value of the big three macronutrients: nitrogen (N), phosphorus (P), and potassium (K).

However, despite being required in smaller quantities, micronutrients should not be overlooked. They play an equally pivotal role in maintaining crop health, improving resilience, and boosting productivity.

What are micronutrients?

Micronutrients are required by crops in minimal amounts, but are vital nutrients for their growth and development. Some essential micronutrients include:

  • Zinc (Zn): Important for enzyme functions and starch formation, as well as aiding in crop maturation. Zinc also plays a role in the synthesis of auxins, the hormones essential for plant elongation and growth.
  • Boron (B): Crucial for the formation and strengthening of cell walls. It also plays a role in sugar transportation and is vital for pollen formation, ensuring successful seed production.
  • Manganese (Mn): Supports chloroplast formation and photosynthesis. It also aids in nitrogen absorption and activates several crucial enzymes in crops.
  • Iron (Fe): Beyond chlorophyll synthesis, iron plays a role in energy transfer within the plant, ensuring that every part gets the energy it needs.
  • Copper (Cu): Vital for chlorophyll production and activates several enzymes in plants. Copper is also necessary for lignin synthesis, a process which strengthens plant cell walls.
  • Molybdenum (Mo): A key player in the nitrogen cycle, it helps crops to utilise nitrogen in its various forms.
  • Chloride (Cl): Critical for osmosis (a process of water balance within a plant) and ionic balance in cells. It also aids in photosynthesis.

Benefits of addressing micronutrient needs

By investing time in understanding micronutrient needs in their crop-growing soils, and addressing any deficiencies if necessary, farmers can reap benefits for their business.

These include:

  • Increased yields: A balanced micronutrient supply ensures every metabolic pathway works efficiently, leading to optimal growth, and increased productivity.
  • Enhanced crop quality: Micronutrients contribute to the synthesis of vital compounds, ensuring better taste, appearance, and longevity.
  • Improved plant health: A well-nourished crop can fend off diseases and pests more efficiently. Properly nourished plants can also better withstand environmental stresses like drought, cold, or excessive moisture.
  • Improved soil health: Proper nutrient balance can promote beneficial microbial activity, improving soil structure and fertility over time.

Recognising micronutrient deficiencies

Every micronutrient deficiency manifests specific symptoms. For instance:

  • Zinc deficiency can show in older leaves as small, yellow leaves with shortened stem lengths, often called “little leaf” syndrome.
  • Iron deficiency typically presents in young leaves – the regions between veins turn yellow while veins remain green.
  • Manganese deficiency can appear as yellow spots or white specks on young leaves.

Inspecting plants and conducting leaf tissue analysis regularly can help pinpoint specific deficiencies. Regular soil tests can also help detect and rectify deficiencies early on in the growth and production of crops.

Value of micronutrientsApplication methods

The two primary ways to deliver micronutrients to crops are:

  • Soil application: Depending on soil type and crop, micronutrients can be added as granular fertilisers, or through fertigation.
  • Foliar application: Direct leaf application ensures quick absorption, especially when soil conditions hinder nutrient uptake. Foliar sprays are absorbed directly, making them a quick remedy for deficiencies. They are especially useful when soil conditions or root health impedes nutrient uptake.

It is important to note that while micronutrients are beneficial, over-application can be toxic to plants. Further information on how to apply fertiliser accurately is available here.

Soil testing: the first step

Before you begin any micronutrient application, it’s crucial to test your soil. A comprehensive soil test not only determines nutrient levels but will also give you insights into pH levels and organic matter content.

This holistic view helps in creating a tailored fertilising plan, which ensures crops get precisely what they need. See here for further information on when to sample soil and what is needed.


While macronutrients might be known for playing the lead roles, optimal crop growth and health can only be achieved with correct levels of micronutrients.

By understanding and harnessing the value of micronutrients, farmers can elevate the health, resilience, and yield of their crops.

So, as you look ahead to the next planting season, develop a robust micronutrient plan by testing your soil and using fertiliser to rectify any imbalances.

Related articles