Johannesteijsmannia Perakensis problems

[JANAIY]

My J Perakensis has some issues. I have 2 and both are in the same fast draining soil, same watering habits, but this one gave me always problems. 
is this magnesium/potassium deficiency or what is going on ?  The long leave is the oldest one. 
I gave it a nutritional leaf spray but don’t think it will resolve the issue. They sit both in darker shade and never get sun exposure. 

Edited December 4, 2020 by JANAIY
Forgot

[Steve Mac]

Hi Jan, @JANAIY

I don't know these palms at all, but just looking I agree with you that it is a nutritional problem. Looking at your very coarse potting mix I would think that you need to ensure that you fertilize them regularly and completely enough. When I kept pots, I had the most success watering them by mixing a surfactant (sometimes) and a fertilizer in a bucket/larger pot and lowering my potted palms into it, when soaked allow to drain back into the bucket and put another pot in etc.

That oldest/biggest leaf may be due to go anyway, but it is funny that the newer ones are smaller. Hopefully someone with one of these can shed more light.

[JANAIY]

Those palms are pretty rare and only a few probably have them. 
It’s odd, however they are all fertilized the same. I will add some liquid fertilizer and see what happens and continue to spray the leaves. I was thinking something specific was missing but researching yellowing leaf gives too many possibilities. I might have to research deeper. 
I like your idea with the bucket, I will try it tomorrow! Thank you for your input! 

[JANAIY]

Those palms are pretty rare and only a few probably have them. 
It’s odd, however they are all fertilized the same. I will add some liquid fertilizer and see what happens and continue to spray the leaves. I was thinking something specific was missing but researching yellowing leaf gives too many possibilities. I might have to research deeper. 
I like your idea with the bucket, I will try it tomorrow! Thank you for your input! 
I found out that it’s probably a Nitrogen deficiency what occurs often with organic soils while it competes with the roots for  nitrogen. It says that the older leaves start first to yellow and later the younger ones. I ordered Nitrogen and hope it will resolve the issue! 

Edited December 5, 2020 by JANAIY

[maxum2610]

I use kiserite (MgO) when the leaves look pale. Usually solves the problem.