Hmm,,,,GOD CAN SEE EVERYTHING!!!!!
Sadly I need a picture and some more info...
Turning yellow where, top down, bottom up, in the middle?
What Nutrients, how often, how much?
In the ground, in a pot, what soil?
I'll go long and pay the vig if it's not P&K toxicity (giving 1 "REP" to GOD). That's the #1 problem I find around here. No amount of added N will fix that at any point!
awaiting further info!