8 Crop Micronutrients Growers Can't Ignore

By Shannon McKee
Published: April 3, 2020 | Last updated: April 23, 2021 01:22:55
Key Takeaways

Understanding the small role each micronutrient plays in the garden will help prevent gardeners from overlooking their importance.

On their quest for huge fruits and flowers, new growers often overlook all of the micronutrients their plants require in favor of providing them with sufficient amounts of the macronutrients—nitrogen, phosphorus and potassium (N-P-K)—they need to grow healthy and vigorous. However, micronutrients help your plants reach for better growth despite the fact they are not needed in high doses.


Balanced crop nutrients require you to have the right amounts of macronutrients and micronutrients in the soil. Micronutrients that you may not be supplying to your plants include iron (Fe), boron (B), copper (Cu), zinc (Zn), manganese (Mn), nickel (Ni), chloride (Cl) and molybdenum (Mo).

Lacking any of these essential plant nutrients may spell disaster for your crops, but thankfully soil testing can be used to determine where you may be needing to add these micronutrients.


How Do Micronutrients Get Depleted?

Micronutrients become depleted from your soil even if you follow a particular fertilizer schedule. There are a few ways that this can happen to your land, even if you fertilize regularly.

For example, you may be growing crops that are high-yielding, which are stripping the micronutrients from the ground because of the amount of growth they go through.

Another reason is that some fertilizers like N-P-K fertilizers contain lower to non-existent quantities of micronutrients as they focus on the macronutrients of nitrogen, phosphorus and potassium. You may also find that your soil is just naturally low on some of these micronutrients—for reasons unknown.



Iron is a potent micronutrient that is necessary for plants to grow and produce food. Iron is used in several enzymes that provide important roles within plant systems. It helps with lignin formation and energy transfer, as well as nitrogen reduction and fixation.

Read also: Pumping Iron: Why Plants Need Iron in Their Diet


The iron used by plants is Fe2+, or the ferrous cations. Iron should typically be applied as a foliar spray as soil applications are not often sufficient for plants.

Your application amount should wet the leaves of the plant. You may need to apply the foliar spray more than once to address the lack of iron in the soil. There are some sticker-spreader agents that can be added to the spray to help it better stay on the leaves to help improve the amount of iron the plant is absorbing.


Boron plays an important role towards the stability of plants. It helps the cell membranes inside of the plant by supporting the structure and function. Some types of soil may be likely to lack boron, so if you notice problems at the growing points of your plants, this may show a deficiency. Boron found in the soil is BO33- anion.

Boron can be applied directly to the ground, but a word of caution in that it is only a small window between a deficiency and toxicity for most plants with this micronutrient. You may want to use an N-P-K fertilizer that has had boron added to it already to ensure you’re applying it in a uniform fashion.

You can use a spray instead, but this is often going to cost you more in the long run. Testing your soil after applying is highly advisable since there is the possibility of boron building up to toxic levels for your next crop.


Copper is involved with several enzymes and works to catalyze reactions that occur during plant growth. It is related to vitamin A production in plants while helping the synthesis of proteins.

Read also: The Role of Copper in Plant Culture

Copper should be applied to the soil, but keep in mind that adding copper to the ground can create a residual effect that could last up to eight years. So, as with boron, it is important to test your soil to ensure your plants are not exposed to toxic levels of copper.


If you’re finding that your yields are limited and should be higher, a deficiency in zinc is probably the culprit. Plants only require a small amount of this micronutrient, but if they are deficient in it, they’re unable to produce the high yields you may be used to seeing with your harvest.

Zinc can be added to your soil or applied as a spray to the leaves. It might need to be applied a few times before reaching the right amount in the soil. Residual effects are possible with zinc as with copper and boron, so it’s best to test your soil before and after applying it.

Some states have even changed the recommended application rate for zinc due to the possibility of residuals.

"Manganese is responsible for a portion of the enzymes that allow a plant’s metabolism to function."


Manganese is responsible for a portion of the enzymes that allow a plant’s metabolism to function. It is also vital for photosynthesis. This micronutrient will help speed up germination and maturity of the plant along with contributing to increasing the amounts of calcium and phosphorus that the plant has to work with for the growing process.

Manganese can be applied alone or as part of an N-P-K fertilizer. It can also be applied as a spray to the leaves. This route will require a lower rate than if you were applying it directly to the soil. As this does not have any residual effects, it needs to be applied annually to your soil if there is a deficiency.


Nickel helps enables the conversion of urea in plants, as it is a vital component of the urease enzyme. It’s also believed to help with nitrogen fixation.

Read also: The Effects of Cobalt, Copper, and Chromium in the Garden

As nickel was only recently added to the list of nutrients essential for a plant’s growth in the later part of the 20th century, there are still some growers who are not certain as to whether it should be considered essential. To have a rounded out fertilizer for your plants, it can be helpful to get one that includes nickel.


Chloride is a valuable plant micronutrient; it helps with photosynthesis and helps with how plants use energy. The chloride anion used by plants is often from chlorine that is often salt-trapped in the soil, found in salt water aerosols or from emissions from volcanoes. Chloride can be added to your soil simply by using a fertilizer that includes it; sometimes it can be found as calcium chloride.


Molybdenum is essential when growing legumes as it’s used in the process of symbiotic nitrogen fixation. It’s also useful for nitrate enzymes in that it can be used for synthesis and reductase. Deficiency is not usually a problem with molybdenum, as it is commonly found in most areas, but there is a possibility it could be depleted in your soil.

This micronutrient should be applied before planting to correct this problem and is available in molybdenized phosphate fertilizers. There is also a spray that can be used on the soil rather than the leaves to ensure the application is uniform. You may find that some seeds are treated with this micronutrient as part of a sticking agent so plants typically receive the right amount of it.

Read also: Essential Nutrients for Growing Cannabis

To achieve maximum yields, it’s important to not only have the vital macronutrients but these micronutrients. For the healthiest crop possible, consider taking the time to test your soil for deficiencies of these micronutrients.

You’ll probably be pleasantly surprised at how improved your crops look after you address any gaps you may have in the soil.


Share This Article

  • Facebook
  • LinkedIn
  • Twitter

Written by Shannon McKee | Freelance Writer, Gardener

Profile Picture of Shannon McKee

Shannon McKee lives in Ohio and has been a freelance writer for several years now, including on her blog, Nicknamed by loved ones a garden hoarder over the past few years, she grows a wide variety of plants in her urban garden.

Related Articles

Go back to top
Maximum Yield Logo

You must be 19 years of age or older to enter this site.

Please confirm your date of birth:

This feature requires cookies to be enabled