I apologize that i just CAN'T say things briefly. Sometimes I can come back a day or two later and produce an "executive summary" with only the most relevant points.
>> How do you know what npk ratio Adenium do need. I have no idea?
Right, I don't know either. Plant scientists and people making a lot of money from hydroponics have their ways.
1. Analyze the plant tissue chemically. Everything except water and CO2 came from the fertilizer, so it must have taken up whatever is in the mature plant. Make the fertilizer match the plant tissue.
2. Grow the plants in a lab setting, probably hydroponically. Measure every milligram of what you put into the water. Measure every milligram of everything in the waste water. Figure that if you put it in, but it did not go down the drain, the plant must have taken it up. Whatever the plant did NOT take up, was in excess.
Be sure to do this for the seedlings, the vegetative growth phase, and the fruiting/harvest stage.
Now apply for even more grant money to do it again for the next plant variety.
3. Get real and do it Rainbow's way. Grow some plants using whatever, say 23-8-16.
Do it again using fertilizer with some other ratio.
Whichever one did better, use as your next starting point and try more of one thing or less of something else. See which works best.
My guess is that the first two methods don't always tell the whole story, and even plant scientists get their CORRECT answers by tweaking the answers from the first two methods using Rainbow's method.
I don't know if any soil testing labs would be willing to analyze the water coming out of the bottom of a pot. They MIGHT be able to tell you that the plant took up ALL the N, but there was left-over P and K.
