How to supplement feeding with sulphate of ammonia?

Hey everyone
Ive noticed a little of my lower foliage could do with a bit more N, so I bought sulphate of ammonia to increase their N without adding even more P or K...

My question is how do i go about administering it? It says it is 21% nitrogen, so should I make a solution and mix it in with the nutes? And if so, what ratio? Or top dress the pots? Or should I just add a... teaspoon/tablespoon? per gallon to my watering cans before I feed? Apologies if this quite noobish... Still my first grow and i dont want to lock out the potassium and calcium by overdoing it...
Many thanks.

IDK, I've never used it, but with that high of an N, I wouldn't use more than 1/4tsp, till you see how the plant reacts.

If it's dry, top dress with it and water it in. Give it a week and see how it looks.

Wet

Watch out for acidification. Sulphate of Ammonia is notorious for affecting the pH of soils significantly, at least in general farming.

cool guys. cheers for the advice. The only bit of info i found said 6g per litre applied over 2m squared, but i think that is for outdoor crops. So im quite apprehensive until i hear from someone who has applied it mid-grow before. It is my second week flowering so i think i'll keep up the veg nutes for the next week or so to buy me time to find a way to apply it.