Of the sixteen nutrients that plants need to grow, develop, reproduce and remain healthy, there are seven that we refer to as micronutrients: zinc (Zn), copper (Cu), manganese (Mn), iron (Fe), boron (B), chloride (Cl) and molybdenum (Mo).
While these nutrients are used in minute amounts, they are just as important to plant growth and development as the macronutrients and secondary nutrients, with some of them playing an important role in controlling key processes and the uptake of macros. For example, molybdenum deficiency reduces nitrogen and phosphorus uptake, while zinc deficiency can reduce overall plant vigor, growth and the uptake of other nutrients.
Here are some of the key roles that micronutrients play:
- Boron is an essential component of cell wall formation and is key to the germination of pollen grains and growth of pollen tubes.
- Zinc aids plant growth hormones and enzyme system, and is necessary for chlorophyll production and carbohydrate formation.
- Copper plays a major role in photosynthesis. This element improves the flavour of fruits and vegetables and can help prevent ergot in cereals.
- Manganese plays an important role in splitting water into its elemental parts, aids in chlorophyll synthesis, and increases the availability of phosphorus and calcium.
- Iron promotes the formation of chlorophyll and acts as an oxygen carrier.
- Chloride promotes crop health and enhances the maturity of small grains in some soils.
- Molybdenum is needed to convert inorganic phosphates to organic forms in the plant and aids in the nodulation of legumes, especially in acidic soils.
Like the macro- and secondary nutrients, a balance of micronutrients is essential for healthy plants and optimal yield, and the over-application of one micronutrient can induce a deficiency of another. High levels of iron, for example, can heighten a manganese deficiency and an excess of molybdenum can induce a copper deficiency.
The micronutrients are also are related to the uptake of macros. Adequate boron is needed for effective nitrogen fixation and nodulation in legume crops, while phosphorus and iron work together to increase the uptake of both of these nutrients. This is called synergy.
Below are more examples of synergy between the Micros:
|Over-application of:||Increases uptake of:|
|Over-application of:||Decreases uptake of:|
It is also good to keep in mind that calcium, a secondary nutrient, increases the uptake of both the macros and the micros. Applied calcium increases the uptake of manganese, phosphorus, zinc, boron, magnesium, iron and potassium.