This is not mine, Andrew saw it on Twitter coming from a Ben Dawkins (@Bennyd111) and we just thought it was fabulous. How useful to quickly see what deficiency your plant is suffering from; I think this is something to be shared, printed out and stuck up on the shed door. Praise be to the Internet, to Twitter and to Ben Dawkins whoever he may be....
For those of you who are a little rusty on the old chemistry you learnt at school, (haha) I have written out what each of the elements translates to....
Hope it helps you tooLove and hugsCarrie