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The 3 Forms of Granular Micronutrients


Not all micronutrients are made equal - The importance of solubility

The importance of micronutrients in growing higher yielding, higher quality, and more profitable crops is well known, although the differences between the types of micronutrients is less so. Not recognizing these differences may mean you’re leaving some yield potential in the field. The key to any fertilizer is how much is available to the plant that growing year. Yield increases are a result of knowing the nutrients applied are in a plant-available form (source) and were applied at the appropriate rate, the right time, and right place.

Plants are only able to take up nutrients that have been dissolved (i.e. water-soluble sulphate forms) into the soil solution. When talking about plant-available nutrients, the solubility of the fertilizer product must be evaluated to ensure the crop is being fed the nutrients it needs. Applying a low-solubility (i.e. less than 30% water soluble) micronutrient has very little benefit to the crop in the year the product is applied. If there is a need of a certain micronutrient for the planted crop and a low-solubility product is used, that crop will show symptoms of deficiency since the nutrient is not readily available.

Forms of Granular Micronutrients

The three forms of granular micronutrients available on the market are sulphates, oxysulphates, and oxides.
  • Sulphates are 100% water soluble and highly available to the crop in the year applied.
    • Quickly provides nutrients to plants and soil build.
  • Oxides are relatively insoluble, making them unavailable to the crop in the year of application.
    • Used to build soil nutrient levels on a long-term basis but not to correct nutrient deficiencies in the year of application.
  • Oxysulphates are a combination of oxides and sulphates within the same granule. The availability depends on the balance of sulphate and oxide nutrients.
    • Effective when needing to correct deficiencies, and to soil build.

Application of Granular Micronutrients

In situations where soil tests show a deficiency for the upcoming cropping season, a sulfate or oxysulphate granular micronutrient should be used in order for the plants to have the crop nutrition required for maximum yield potential. Placement is key for copper, zinc, and manganese as even in the soluble sulphate form these nutrients only move through diffusion. The granules should be placed in the seed row or in close proximity to the seed row to ensure the roots of the plants intercept these feeding sites.
  Levels in soil (ppm)
  Deficient* Marginal* Adequate
Copper 0.0-0.3 0.3-1.0 1.0+
Zinc 0.0-0.5 0.5-1.0 1.0+
Iron 0.0-2.0 2.0-4.5 4.5+
Manganese 0.0-1.0 - 1.0+
*soil micronutrient range levels

All three forms of granular micronutrients have a place for specific circumstances in a cropping system. The most important thing is to use the correct form of micronutrient for the expected results. For response in the year of application you need to use a sulphate or oxysulphate form of the micronutrient you are applying for the correct operation or situation. When choosing a product, ensure that the solubility is known to properly expect the desired results.


NexusBioAg Micronutrients

NexusBioAg granular micronutrients are of the oxysulphate form, supplying nutrients for immediate plant availability, while the also helping with soil buildup and extended plant needs. Our low analysis micronutrient products ensure a better distribution throughout the fertilizer blend. With optimum water solubility the products prove excellent plant availability and are compatible with all fertilizer blends.


Benefits of zinc:

  • Zinc is an important requirement needed during seed development and formation.
  • Zinc is essential in a wide range of plant functions as an enzyme co-factor, in protein synthesis and protein structure, hormone regulation, early root development, energy production and is key for seed formation.

Deficiencies result in:

  • Shortened internodes
  • Stunted plants/leaves
  • Reduced seed set

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Benefits of copper:

  • Copper is essential for cell wall strength, specifically in the anther where the viability of pollen formation is crucial to the yield of the plant.
  • Copper is important for chlorophyll production, protein synthesis, respiration, standability and the efficient use of nitrogen.

Deficiencies result in:

  • Leave tips that spiral or twist
  • Leaves that are light green in colour
  • Poor standability

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