Micronutrients: Part 1

Micronutrients Part 1: Nothing Micro About Their Impact!

Hi everybody! Welcome to this installment of “let’s talk about elements”! This post is dedicated to our tiny friends in the fertilizer world: micronutrients! There are quite a few; I don’t want to be a BORON you (...yes I am really happy about that pun), so I decided to break the nutrients into two separate blog posts: this post is background of the micros, and part two will go into the nitty gritty details. When we say micronutrients, we are referring to the following elements:

Manganese (Mn)      Boron (B)
Copper (Cu)     Zinc (Zn) 
Molybdenum (Mo)  Cobalt (Co)
  • Some say iron (I classify it as a secondary, separate post on iron)

Apologies in advance for all the puns related to the elements.

Not your tomato garden: why micronutrients are important for your hydro garden

It’s quite amazing the accommodations we must make as cannabis farmers that don’t use soil. If you read my post on types of water sources, I mentioned that soil-based growing has a little bit more room for error changes (the soil is a “buffer” of sorts). As you can tell by the name of these nutrients, micronutrients do not need to be in high concentrations (sometimes in the parts per million, or ppm). In fact, many of these nutrients in high quantities would be TOXIC! It’s just like cheeseburgers…small quantities and they’re great…too many and your doctor is going to yell at you. Anyway, in soil media, usually the soil itself has these metals already present, and thus would not be fortified. Now of course, if you deplete the soil nutrients, you would need to supplement to get your micros.

Obviously, without soil in a hydroponic garden, you are robbed of these essential micronutrients. Thus, it is of paramount importance to make sure your plant is getting the supplemental micronutrients it needs.

Cool Story Bro. “Micro” = just use less nutes, and it’s no different than N-P-K or Ca……

I wish it were that simple. To make things more complicated, not all micro sources are the same. It has to do with nutrient mobility – micros tend to be very immobile (this is a good thing, imagine if all the heavy metals in the world were able to move quickly through the soil…we would be in trouble). The easiest way to explain this is via the periodic table: most of the micros are called transition metals (in the middle section of the periodic table). These metals have super high affinities for the charged particles in soil (or in your case, the anions that are present in your res or at the root zone such as phosphates, sulfates, etc.). So instead of going into the plant, they would interact with these things, and not be taken up by the plant. The issues I’m describing can be similar to “nutrient lockout” you see with calcium or phosphorous; but at super small levels you may not even see it happening!

Chillax…We have Metal Chelates to Save us!

I set up the above title to hopefully make you say, “chelates” wrong (if you said “chillates”…got ya!). Chelates (pronounced key-lates) are a special way to describe these micro metals. Instead of using an iron source like iron (III) sulfate (which would likely get stuck in your res and not be plant absorbed), iron comes in “chelated” form: Fe-EDTA, Fe-DTPA, Fe-EDHHA, etc. Chelated metals are much easier for the plant to be able to take up in a usable form (Wallace, A. et al. Soil Science 1957, 84, 27–42). An entire separate post will be devoted to this, but just know that when you look at Elite Base Nutrient A, all those “EDTA”-based nutrients are essentially the security escorts for the micros to get into the plants! Quick note: not all transition metals require chelation. So, let’s get into it now!

The Iron-y: Fe a micro or a macronutrient?

 Much of the world considers iron a micronutrient – as a scientist, I actually lump it into the “secondary macros” category, because its deficiencies are similar to what we see in secondary nutrient deficiencies. The take home message about iron (discussed in detail in a future post): Fe-EDTA = chelated iron = good for your plants in small quantities for most water systems. Iron chlorosis is the yellowing of the leaves with still green veins; your plant needs more iron if this happens!

That’s all for this post, stay tuned for part 2 of the microtalk!

Who is Dr. NPK? With a PhD in Chemistry from UC Irvine, Dr. NPK was instrumental in developing the Elite Nutrient line.  Learn more about him here.