Chelates

Our Mission

When we formed Plant Fuel Nutrients, our goal was simple. Make growing easier for the grower not only by creating a simple 3-step growing system, but also, and most importantly, by educating the growers. Most nutrient companies out there are capitalizing big-time on a lack of knowledge, and by using misinformation to sell products that growers frankly don’t need. Our goal with this blog is to pick a topic each week to educate growers about. We hope that you enjoy reading it as much as we have enjoyed creating it!

Chelates

What are they?

The term chelate comes from the Greek word which refers to a lobster’s claw. It is in this way that we can think of a chelate, a micronutrient (generally metal, represented by the M in the illustration below, such as Mn, Mg, Cu, Zn, or Fe) surrounded by a chelating agent or a ligand. There are many different kinds of chelating agents that can be used with respect to

fertilizers. There are organic, or carbon-based ones, such as citric acid, humic acid (shown to the left) and fulvic acid, as well as a variety of amino acids. There are also some synthetic ones, such as EDTA, (shown to the right) which is the main chelating agent used in many fertilizers.

This ligand, or chelating agent, surrounds the metal ion and keeps it from reacting with other ions in the fertilizer solution, such as the phosphate or hydroxide ion. There are also many

other kinds of naturally occurring ligands that are produced by plants to help them to uptake micronutrients. All plants can release substances called exudates from their roots, which basically act as a vehicle to grab ions from the soil solution and bring them into the root. One such natural chelating agent found in root exudates is mugineic acid, a kind of non-protein amino acid, which can convert iron from its unavailable Fe3+ form to its plant available Fe2+ form, and bring it back into the plant through the roots. Humic acid as well as fulvic and citric acid, can be thought of as earth’s natural chelators. These natural acids stabilize the availability of nutrients in the soil solution. They have large, complex molecular structures that allow them to work in the same manner as EDTA or other synthetic chelating agents, forming a “shell” around a metal to keep it from becoming unavailable to plants.

What do they do?

As I stated in the introduction, chelates basically help to keep metal ions from reacting with other ions in fertilizer solution as well as in the soil solution, thus turning into a plant-unavailable form, or precipitating out of solution completely. Put simply, chelates are generally good for nutrient availability when it comes to fertilizer applications. This chelation also helps to keep nutrients available through a wider range of pH, since chelated micronutrients are less likely to react with other ions in the soil or hydroponic solution and either precipitate out of solution or oxidize (lose electrons) into plant unavailable forms.

What many nutrient companies are claiming

Many Nutrient companies out there are capitalizing on misinformation, and using it to sell products that growers really don’t need. As I have stated above, fertilizers containing chelated micronutrients are usually a good idea, because of their assistance for nutrient availability, but most any fertilizer that contains micronutrients will contain some sort of chelate to keep the micronutrients from precipitating out of the fertilizer solution while still in the bottle. This being said, there is very little, if any research that points to chelates being able to pull excess nutrients out of a plant. When a plant takes up nutrients, it converts those nutrients into other forms that can be used to produce plant matter, or other compounds, such as chlorophyll, it doesn’t just hold onto them in their salt form (such as NO3-). The uptake and metabolism of nutrients in plants can get complicated very quickly, and will likely be the subject of a later blog post.

Conclusion

There are many different chemical compounds that can act as chelating agents, and the term “chelate” can mean many different things. Some companies use EDTA and other chelating agents in their fertilizers, but we choose to use humic, fulvic and citric acids as our “chelating agents”. Research has shown that these organic acids can allow metals to be more plant available in the short term than can EDTA and other ligands. This is the reason why our transition fuel is black, because it contains humic acids, along with the sea kelp and other compounds. Humic acids are naturally found in soil organic matter, which is why this part of the soil solution has such a good Cation Exchange Capacity, as well as a good ability to hold nutrients, and are just one of many natural chelating agents that are present in the soil solution. So, long story short, just because our fertilizer doesn’t say “chelated micronutrients” on the bottle, does not mean that our products do not contain chelated minerals, because they do, just with organic acid complexes rather than EDTA.

For further reading, Check out some of our references:

https://humates.com/pdf/ORGANICMATTERPettit.pdf

http://edis.ifas.ufl.edu/hs1208

http://www.jhbiotech.com/plant_products/chelation.htm