# Chelated Micronutrients

- Link: https://rd2.co.nz/chelated-micronutrients/
- Published: 2023-03-29T00:37:37+00:00
- Author: RSF Admin

Written by Donald Lester

Agricultural Scientist Donald Lester details the benefits of highly efficient chelated
micronutrients—which aid in enhanced plant growth and greater yields—and defines
the various types to help you choose the very best option for your indoor garden
system.

Plants need the essential nutrients nitrogen, phosphorus and potassium—the N-P-K
on fertilizer labels—in large amounts, so these are referred to as macronutrients.
Plants also need essential micronutrients (also known as trace minerals) such as
calcium, zinc, magnesium, iron and manganese. Micronutrients come in many different
forms that affect their solubility (i.e. dissolvability) in water and their uptake
and usage by plants.

Micronutrients commonly react with other chemicals and get “tied up” or precipitate
in the soil. Once this happens, the micronutrients are insoluble in water and will
not be absorbed or used by the plant, at least not until microorganisms or weather
breaks them down into a usable form. So, you could literally add a lot of one micronutrient
to the soil, but the plant will use only a small amount. A good example of this 
phenomenon can be seen with the soft mineral gypsum. Every year growers apply gypsum
to their fields by the ton, but since it is not very soluble in water, only a very
small amount of calcium is available to the plant. It takes a long time for soil
microbes and weather to break down these compounds so that plants can use them. 
Foliar applications do not suffer from this phenomenon (table one).

| **Nutrient** | **Crop** | **Foliar** | **Soil** | **Citation** | 
| Zinc (ZnSO_(4)) | annual crops | 1 | 12 | Lingle & Holmberg (1956) | 
| Phosphorus (H_(3)PO_(4)) | beans, tomatoes | 1 | 20 | Witwer, et al. (1957) | 
| Iron (FeSO_(4)) | grain sorghum | 1 | 25 | Withee & Carlson (1959) | 
| Magnesium (MgSO_(4)) | grain sorghum | 1 | 100 | Krantz (1962) | 
| Magnesium (MgSO_(4)) | celery | 1 | 50 to 100 | Johnson, et al. (1957,1961) |

Table 1. Relative amounts of nutrients are needed for comparable effects in the 
plant, by the method of application.

Fertilizer manufacturers produce several different forms of micronutrients, such
as salts, oxides and chelates.Chelated micronutrients are becoming popular because
of their high efficiency. Knowing a bit about the various types of chelated micronutrients
can help you choose the one that is right for you.

## **What is a chelate?**

Chelation is a term that describes an encapsulation process. A mineral, like calcium,
for example, reacts with another material to form a protective shell around the 
desired mineral or metal (in this case, calcium).The word chelate derives from the
Greek word “chel”, meaning a crab’s claw, and refers to the pincer-like manner in
which the mineral is bound. Some chelating chemicals are shaped like the letter ‘
C’ and surround the mineral with just one molecule.This type of binding is called
a “complex”. When two molecules of the same material surround a mineral, it is known
as a chelate. It is important to note that some minerals, like boron or molybdenum,
have only one chemical bond and are thus limited to forming only a complex. Strictly
speaking, boron and molybdenum cannot be chelated minerals but they are often presented
and sold in the market as chelated minerals.

Chelates need a “glue” to hold the protective shell in place. Some chelates use 
sodium for this purpose, but adding sodium can be detrimental to plants. In general,
the amino acid chelates use organic acids like citric acid. There is an important
distinction to be made here about the use of the word organic. In chemistry, the
term organic means the material contains carbon. In the organic foods world, the
term organic refers to foods produced without pesticides, synthetic substances, 
sewage products and other restrictions.

Chelates are molecules with a neutral charge, which is very important. Micronutrients
normally have an electrical charge on them. For example, calcium and magnesium are
both +2 charge. Soil is generally negative in charge, especially clay soils. This
means that calcium and magnesium will likely react with the soil and be insoluble
and not available for plants to use. Moreover, since they are the same charge, calcium
and magnesium compete with each other for entry into the plant.

Pores on the leaves of plants (also known as stomates) are negatively charged, so
positively charged molecules trying to penetrate the plant get tied up at the stomate
entrance, thus slowing absorption. But the interaction with chelates is very different.
The neutral charge of chelated minerals allows them to enter the stomates unimpeded.
Research into nutrient uptake has shown that some materials applied to leaves do
not enter the tissues but instead remain stuck to the leaf surface, like house paint.
Subsequent chemical analysis of these tissues would show similar nutrient levels
as those tissues that had nutrient penetration. In light of this oversight, researchers
now apply nutrients to the leaves and then analyze the fruits to measure the amount
of nutrient movement inside the plant.

There are several types of chelates. One of the most common forms is Ethylene Diamine
Tetraacetic Acid (EDTA), which has been on the market for years. EDTA is a large
synthetic molecule that binds very tightly to minerals and resists chemical interactions—
desirable characteristics for chelates used in the soil. But this strong bonding
characteristic can be a negative attribute once EDTA is in the plant. EDTA binds
tightly. In fact, when people have heavy metal poisoning EDTA is injected into their
bloodstream to chelate the metals and filter them out. Obviously, patients do not
want EDTA releasing heavy metals back into their bodies prematurely. 

In addition, EDTA can solve one plant’s nutrient deficiency and at the same time
cause another. EDTA has something of separation anxiety; it must always hold on 
to something. For example, iron EDTA will cure the iron deficiency in plants, but
in order for the EDTA to release the iron, it must hold onto something else. Often
EDTA will take up manganese in order to release the iron, thus causing a manganese
deficiency. Furthermore, EDTA is known to take calcium from cell walls in both plants
and people. For this reason, people put on EDTA are often instructed to take calcium
supplements as well. Plants losing calcium in this manner (primarily from their 
cell walls) visually manifest the loss as wilting.

Another category of chelate is the amino acid chelates. There are 20 amino acids.
Amino acids are the building blocks of protein. Amino acids are moderately strong
chelating agents. Once inside the plant, the mineral is released, and the leftover
amino acids that form the protective shell are used by the plant as a source of 
water-soluble nitrogen. After all, amino acids are building blocks in cell machinery.
Everything is used, and nothing is lost. Conversely, EDTA is a synthetic molecule,
and plants do not naturally use EDTA. It’s sort of like trans fat; the human body
doesn’t know what to do with it.Amino acid chelates are generally systemic in the
plant, meaning they move and travel to where they are needed.

They can do this because amino acids are recognized by the plant as building blocks
and are used in nearly every tissue in the plant. Amino acid chelates are available
as liquids or powders and generally available for use in organic food production.
Glycine chelates (also known as glycinates) are a subset of amino acid chelates.
Glycine is the smallest amino acid, and it is often used as a chelating agent. Since
glycine is small, it makes a small final product that passes through leaf pores (
stomates) more easily than other larger molecules, thus enhancing plant uptake. 
And don’t forget glycine chelates have glycine, which is an amino acid. When glycine
is separated from the mineral in the plant, the plant uses glycine.

Glycine chelates are sometimes used in wine production because they supply not only
the desired nutrients but the glycine also supplies Yeast Available Nitrogen (YAN).
This means that the yeast can break down the glycine and use the nitrogen in the
formation of its cell walls. Because chelates enter the plant easily, they are extremely
useful for quickly correcting nutrient deficiencies. As a rule, chelates are very
safe for the plant. The amino acid chelates (glycine chelates included) require 
large amounts of product to be applied in order to be toxic to plants. But care 
must be taken to avoid phytotoxicity or burning of plant tissues with EDTA.

## **Using Amino Acid chelated micronutrients**

Amino acid chelates are especially suitable for greenhouse and hydroponics systems
because they are usually certified organic, readily available for uptake by plants
by both roots and foliage and generally are not phytotoxic. For example, in aquaponic
systems where fish are integrated into the hydroponics system, it is important that
nothing synthetic enter the tissues or meat of the fish.Therefore, the use of organic
materials is an obvious choice, and the amino acid chelates can be applied directly
to the foliage or to the nutrient solution for immediate correction of nutrient 
deficiencies. When shopping for chelated minerals, look for the characteristics 
listed below.

## **Shopping for chelated micronutrients**

**Desirable Characteristics**

 * Formulation is safe for plants
 * Does not promote other deficiencies
 * Readily available to the plant
 * No sodium
 * Organic certification

**Undesirable Characteristics**

 * Formulation is prone to burning
 * Needs ion replacement to release micronutrients
 * Slow uptake
 * Contains sodium
 * Not organically certified

To view the original paper, [**click here. **](https://rd2.co.nz/wp-content/uploads/2023/03/Chelated-Micronutrients-1.pdf)