Hi
I was thinking of switching to a different fertilizer, one that would be closer to the NPK ratio 5-1-3. But this would mean it wouldn't necessarily be a citrus fertilizer. My question is, what should I look in it for?
What nitrogen form? Is urea fine?
Which nutrients and what percentages of them? Chelated form, EDTA?
What else? Should it contain something natural like guano, seaweed?

Hi,

I use this one , and have good results with it.

http://www.scottsprofessional.com/en/universol-green.html

Look at the technical information.

Grad85, I would like not a specific fertilizer recommendation, but a composition recommendation, because we don't have the fertilizer you recommend in Lithuania. And I also prefer liquid fertilizers, because it's much easier to measure them with syringes when preparing a solution.

My current fertilizer has such composition:
6% Nitrogen (of two kinds)
4% P2O5
6% K2O
0.01% Boron (water soluble)
0.002% Copper (water soluble, chelated EDTA)
0.06% Iron (water soluble, chelated DPTA)
0.01% Manganese (water soluble, chelated EDTA)
0.001% Molybdenum (water soluble)
0.002% Zinc (water soluble, chelated EDTA)
No magnesium whatsoever, but I use epsom salts.

Is such composition good (as far as trace elements go, not the NPK)?

I usw the same type as Grad85, but not clear yet about the same ratio when speaking of citrus in pots and not in open field

The trace elements look good to me.
You could use some seaweed ore maerl ,once or twice a year.

There is a citrus fertilizer by COMPO, that I would really like to buy, it has an NPK 7-3-6, but unfortunately they don't sell this fertilizer here either... I have an orchid fertilizer by this company and it seems to work great for my orchids.
By the way, the COMPO fertilizer contains Sulfur. Is sulfur necessary for citrus?

Well, yes. Sulfur is need, but as trace element only. Most fertilizers don't have the need for sulfur on citrus, because of regular sulfur sprays against certain fungal disease prevention. Thus also we as home growers can use sulfur sprays, as nutrient supply for the plant, and fungal protection.
If you can get, look for HaKaPhos green... Don't know if you can get it, but: It's also from Compo and good for Citrus.

Well, the best I could find was NPK 7.7-3-5.1
What do you think?

Hello again.
There is a fertilizer that has the NPK ratio 8-2-5. But the problem is that it has no trace elements, except MgSO4.
Now I do have this powder, which is a trace element fertilizer.
It contains:
9% MgO;
4% Mn chelate EDTA;
0.5% B;
0.1% Mo;
1.5% Cu chelate EDTA;
1.5% Zn chelate EDTA;
4% Fe chelate EDTA.
Now, how much would I need to add of this powder to a 0.5l bottle of the fertilizer (which I would guess weighs about 600 gr)?
Would I risk having excess Mg?

The amount of trace elements used is in a ratio to the amount of nitrogen used. Therefore, it depends on the nitrogen percentage in the type of fertilizer that you are using. It is going to be a MICRO amount if you intend to add it with every fertilizing. Listed below is a link for the use of STEM (Soluble Trace Element Mix), which is fairly equal to your trace element mix. I believe you would be safer to apply trace minerals as a foliar spray, perhaps once every 3 months. - Millet (615-)

http://www.alliedbotanical.com/pdf/Petersstem.pdf

Can I dissolve 10g of the trace element mix powder into 90g of water and have 100g of 10% solution, so that it would be easier for me to measure liquid with a syringe as opposed to weighing dry powder? Or once it's mixed with water it expires or something?

When mixed with water the minerals will stay in solution. If the bottle is capped it should be fine for a long time. - Millet (613-)