No offense but unless you put the whole "Cake" into 1 tank, you have no idea what the chemical content dose of each "pc of Cake " is, when you are just sprinkling dry frets on clay.
Even something as controlled as a aspirin tablet can not be broken in 1/2 and insure each pc. is 50% dosage.
I'm not posting to be difficult, just trying to understand how how this method can work with 'Burning' some plants along the way?
Great post! Yes, I agree you want to mix the dry ferts thoroughly before starting to work them into the clay.
On the fertilizer - yes this can be an issue. You have to blend, blend, blend, blend, blend....until it your hands are exhausted (or get a pasta machine for a little easier process). If you just put one fertilizer in a hunk of clay, set that aside, and repeat and just kind of halfheartedly push them together, you are going to have this issue. There will be more of this chemical in one piece, more of another in a separate and none at all in other hunks. Even with all the blending, it'll be impossible to know exactly what is in each tablet without analysis. The goal is to get it blended well enough that it's a nominal discrepancy.
You aren't going to burn any plants if you mean by excessive fertilizer. There isn't enough fertilizer to worry about it in each piece. I've dumped a hole batch in my tank before 300+ tablets and never had an issue other than a clay rich substrate (which is messy when uprooting).
What I do now is this (also because it is much easier and the clay doesn't mold over time as it likes to do in a wet form):
1. Take out wet clay and run it through the pasta machine or a rolling pin until it is thin and let dry. Place these in the cuisinart and pulverize the clay (or in a baggie and roll over them to crush).
2. Put all the fertilizer in a container. Add in a cup of water, just a bit at a time to blend it into a paste and eventually a liquid. I've down the phosphates separate from the other chemicals before worrying about
whole precipitate thing. Now, I don't bother.
3. Add in clay a bit at a time until you get it into a pliable form. Basically, similar to Wallace's method.
One question I have - won't adding phosphates and Micros in one recipe STILL bind up the iron (and perhaps phosphates)?
Wasser - on mixing the phosphates and other chemicals- This is what I've found over the years. My water is really high in iron, yet when I add phosphates in the water column, it's effective and doesn't become unusable. Also, I've been mixing phosphates and micros for years in a liquid solution and have never had an issue with it. Plants grow just as well as using separate containers. There is a bit of residue on the bottom of the bottle, but it was never much.
Then, I looked at mineralized soil. People have been adding red clay and phosphates for years this method. Red clay has a lot of iron in it and should do similar as a root tablet. Add that to the rivers and creeks that are full of clay and phosphates in the dirt and it just made since to me that it won't be an issue.
So, I decided to test my theory. In the first set, I didn't add phosphates and saw growth, but it wasn't as quick as I hoped for. I went ahead and added phosphates to the second batch and the growth was stronger, healthier and faster. I think precipitate is not as big of an issue as we perceive. Of course, this is all conjecture.