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As we discussed in our previous blog post, plants require large amounts of macronutrients to grow and thrive. The secondary nutrients – calcium (Ca), magnesium (Mg) and sulfur (S) – are just as vital to plant growth and development, though they are required in lesser amounts than the macros.

Like the macros, the secondaries each play a big role in a crop’s health.

  • Calcium is important for continuous cell division and formation as it regulates hormonal activity and increases both fruit set and quality.
  • Magnesium, the center molecule of chlorophyll, improves the utilization and mobility of phosphorus and helps the plant form and transport sugar and starches.
  • Sulfur is an integral part of amino acids; helping in the development of enzymes, vitamins and oil contents and aiding in seed formation.

Nutrient Interactions

When making a nutrient plan, it is important to be aware of how the secondaries work with, and sometime against, each other. Having this knowledge, and striving for a healthy balance of nutrients, can help you avoid deficiencies induced by interactions.

High calcium levels, for instance, can reduce the availability of magnesium, while high levels of magnesium can induce a calcium deficiency. Therefore, anytime magnesium levels are greater than calcium, it is imperative that calcium be added in precise quantities to ensure a healthy crop.

As well, proper application of sulfur has been known to raise the magnesium levels in the tissues of the plant and, interestingly, tests have shown that where soil sulfur levels were low and phosphorus levels were high, magnesium levels in the tissues were low – even though the soil magnesium levels were high. High levels of magnesium in the soil can also create a demand for more phosphorus.

Here are more examples of antagonisms and interactions between the secondary nutrients and the micro- and macronutrients:

Over application of: Induced deficiency:
Calcium Boron
Calcium Zinc
Calcium Phosphorus
Calcium Iron
Magnesium Nitrogen

Balancing nutrients to grow a good crop can be a challenging task, but your OMEX Representative can help. Contact your rep today to find out more about the Primers, Starters and Foliars that can help you meet your yield goals.

In our next post in this series, we will discuss the interactions between the micronutrients.