Posted: 05/02/2015 at 23:12
The NPK values are the ratios to each other and nothing more. It should really be written N:P:K but this forum will mess-up certain combinations of colons and numbers and display emoticons instead, so I'll use the dash below!
For example, a 10-6-4 will have 10 parts Nitrates, 6 parts Phosphates and 4 parts Potash.
So, for solid fertilizers, 100 grams of a 10-6-4 would have 50g Nitrates, 30g Phosphates and 20g Potash.
If supplied as a liquid, 1 litre of a 12-8-10 woulld have 400ml N, 267ml P and 333ml K.
Not sure if that helps, but there you go.