Marble chips on Kovachii's potting mix?

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From very little to too much.
:wink:
I knew you would ask that.

I don't have numbers for it.

As I said the base nutrients were MSU alternated with Calcium Nitrate.
There is a small amount of ammonia N in that supply.
To verify if more ammonia would help the unknown nutrient requirements of the kovachii I began to slowly add increasing amounts of ammonium nitrate over time.
I did not see any change until I noticed what I considered to be less good growth.
Less good in this case would be darker green leaves that had less stiffness and were softer and thinner. In addition I started to see an increase of older leaf yellowing and drop and the first instances of what appeared to be bacterial leaf infections.
At that point I stopped the use of ammonia and growth stabilized back to where it was.
Based on that observation I deduced that ammonia N was not beneficial for the seedling kovachii.

The above is based on using MSU and not K-lite. How the lowering of the potassium supply relates to the effect of ammonia I can only guess. I would guess that if you increase the ammonia content of K-lite then you may need to increase the potassium content of K-lite.

Well you need to be careful with ammonium nitrate as it's all N. If you just add the AN without reducing the same amount of N from the Calnitrate you could easily reach a stage where you're overdosing the N and end up with the above symptoms. I use something similar to the MSU but with the Calcium nitrate separate so I can halve the Calnitrate and increase the ammonium nitrate. (both to reduce free Calcium and increase NH4 - most Ca is now supplied as lime). I have no issues with sappy or weak growth with anything. On top of that I cut the above mix with 50% urea based feed so there's plenty of ammonium going in. (relatively) And plenty of K too by the way...Ha!
 
Well you need to be careful with ammonium nitrate as it's all N. If you just add the AN without reducing the same amount of N from the Calnitrate you could easily reach a stage where you're overdosing the N and end up with the above symptoms. I use something similar to the MSU but with the Calcium nitrate separate so I can halve the Calnitrate and increase the ammonium nitrate. (both to reduce free Calcium and increase NH4 - most Ca is now supplied as lime). I have no issues with sappy or weak growth with anything. On top of that I cut the above mix with 50% urea based feed so there's plenty of ammonium going in. (relatively) And plenty of K too by the way...Ha!

I made the correct reductions to keep the N constant at 125 ppm.
I kept the Calcium Nitrate separate.
I'm only addressing the results I found for growing P.kovachii not other orchids in general. Are you growing kovachii under your high ammonium supply?
Don't misunderstand my comment about growth being "less good". I did not say the growth was weak or sappy, I said I noticed the growth was less good. It was still good growth with the ammonia but not what I considered optimum and was heading towards problematic conditions.
 
Limestone varies in chemical composition. It can be almost pure calcium carbonate, as your marble is. Blend in enough magnesium carbonate and we call it dolomite. If it is more granular it could be called sandstone, especially if there is some quartz or feldspar content too. There is no clear line between any of them, and they can contain almost any other minerals in some quantity too. They are sedimentary rocks, so whatever wears off rock and flows downstream or builds up on the sea floor from shells etc. can go into limestone. Marble is what limestone becomes given enough pressure, heat and time. The chemical composition does not change so can be anything in the limestone range, it just becomes harder and more crystalline, so the surface area and reactivity is reduced by some amount. Much of what a sculptor or builder would call marble a geologist would call limestone. Obviously, this all makes generalizations about them hard to make. If what you have available is some form of marble just be aware you may need more of it in the mix, or in smaller pieces, to get the same results. The activity will depend on media, water chemistry and watering practices too, adding another set of variables. Use what you can get, observe the results, and make changes if needed. Anyone's conditions are a unique experiment.

very interesting and helpful, thanks.
 

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