K-lite and CHC (Coconut Husk Chips)

[katzenhai2]

Hello,

I use CHC (Coconut Husk Chips) as a substrate for my Paphiopedilum. As I know about the problem with potassium (K) accumulation I wanted to mix my own K-lite fertilizer. I live in Europe and it makes little economic sense to import it. I know about the discussion about CHC, whether good or bad. I've been using it on and off for 10 years.

I have calcium nitrate and magnesium sulphate.

Calcium nitrate:
N : 15,5%
CaO: 26.0%

Epsom salt:
MgO: 16%
S : 13%

My liquid orchid fertilizer has 14-8-7-2 (N-P-K-Mg). There's a calculator on Ray's site but I'm unsure about the units in the calc:
https://firstrays.com/k-lite-knock-off-calculator/

Also some general questions:
1. Can I just add the Ca and Mg to my liquid fertilizer?
2. Have read in German forums that calcium nitrate should not be mixed directly with a fertilizer because it would bind with the phosphate and precipitate as a source of calcium. Therefore calcium nitrate should only be administered alternately with other fertilizers. That would make it impossible to mix it with my liquid fertilizer (to lower the K) !?

 

[Ray]

If you mix them in the diluted solution and use it right away, it should not be a problem.

 

[wongwong]

Cation "attracted" on medium static negative charge cannot be leached by water alone, but exchanged by other cation in solution.

calcium not suggested to be mixed as concentrate
Ca &P bind at higher(neutral) pH

 

[katzenhai2]

I use a liquid fertilizer 14-7-8-2 (N-P-K-Ca) from a professional orchid grower. According to the instructions I should put 10ml of this in 1 liter (1,000ml) of water for each watering. However it isn't specified how often.

If I understand correctly it means that 14% of 1,000 ml fertilizer is 140g (140,000mg) of N. If I use 10ml of the fertilizer then I have 1,400mg (=1,400ppm) in my water pot? Or is my calculation wrong? The EC of the solution is ~500-600 µS.

 

[terryros]

Ray, or one of his online calculators, will tell you exactly. When I run what you have given it is a very high ppm N. Yet, the EC is more in line with a solution that is about 75 ppm N. Even 1 mL/Liter would be a solution that should have an EC that is higher than 500-600.

 

[TyroneGenade]

I use a liquid fertilizer 14-7-8-2 (N-P-K-Ca) from a professional orchid grower. According to the instructions I should put 10ml of this in 1 liter (1,000ml) of water for each watering. However it isn't specified how often.

If I understand correctly it means that 14% of 1,000 ml fertilizer is 140g (140,000mg) of N. If I use 10ml of the fertilizer then I have 1,400mg (=1,400ppm) in my water pot? Or is my calculation wrong? The EC of the solution is ~500-600 µS.

It is 14% of 100 gram is N, 7% per 100 g is P etc... That is typically how NPK are expressed. The fertilizer must supply actual concentrations on the bottle. It is very unlikely to be a 14% solution , that is, 14 g N per 100 ml. That would mean something like 62 g nitrate per 100 ml.

 

[Ray]

I cannot speak for Germany, but in the US, the analysis is provided in weight percent of elemental nitrogen, phosphorus as P2O5 and potassium as K2O, with all other minerals as elemental percentages.

14% is, indeed, 140000 ppm. If you dilute that 10 ml/L (1%), then your solution will be 1400 ppm N. Personally, I’d never go over 1ml/L, or 140 ppm N for feeding every 7-10 days, but you may find that you can do better after making minor adjustments from there.