Nitrogen Deficiency Indoor Soil

I grow small/stealth with 16 oz party cups soil, CFL flower cycle from seed that being said once the plants get about 3 to 4 weeks old and the buds have been growing a week or so the bottom leaf start turning yellow typical Nitrogen deficiency looking kinda thing, I guess it is because there isn't much soil to go off of so they suck up the nutrients really quickly and apparently Nitrogen is the fist thing to deplete and I have tried using green tee as a top coat and that works well enough but there is still a bit of yellow here and there so my question is does anyone know of a nitrogen source of nutrients that I can use that will not burn my plants because that is a concern to me do to the small container and as I have learned from past mistakes its really easy to burn them, so a safe and effective source of nitrogen anyone?

I like Blood meal for Soil.

IMO- The best thing for small stealth grow is Hydro.
It's easy to get water any time. lots easier than soil, and no soil mess.
Better results than soil. IMO- a little quicker than soil.
The down side is the Hydro learning curve, and equipment.

Good Luck on Your Grow.

PG,
Worm castings are organic and very rich in N and other nutrients. That's what I use in such situations...
JD

Thanks for the tips

try this as a foiler spray. stinks like ass but works for me