If the bottom leaves are dying from the midrib up its N def.
If the bottom leaves are dying from the Margin (edge) up in a V like pattern it's a K def.
If the leaves turn yellow and look almost striped, (the leaves maybe yellow and the veins greener) you have a Mg def < if you suspect this check to see if the top leaves are serated and pointing up! If they are it's Mg. If they aren't I'd look at N and K more.
It's nearly impossible to diagnose plant problems without pictures though. Oh and don't pee on your plant. I know you are probably kidding but pee has a ton of N in it and will probably kill your plant. Ever notice how the grass is all fried where you pissed the night before when you were drinking?
Exactly!
Chronic
good luck