Yellowing, brown splotches - 3 wk seedling

What does this look like? I am thinking maybe N deficiency?? It is only happening on her lowest, oldest leaves, new growth looks ok. Grow medium is soil (cheap potting soil, nute content not known). She did get some light burn due to touching a CFL with some of her upper leaves but that doesn't explain what's happening to these lower ones. Only thing I've given her besides aerated tap water is some Epsom salt.

Here's some closeups of the leaves in question.


And here's some pics of the entire plant. Labeled in orange are the light burned areas that accidentally touched a CFL. I already know about these and you can skip over them when assessing the plant. It's the lowest, splotchy leaves I am most concerned with.

Last week these same leaves had an odd curl (preying?) to them and it was suggested to me to try some Epsom salt.. I now wonder if the yellowing is actually FROM the Epsom.. I only added a little but she's just a tiny thing, maybe I over did it.

xinjun,
So you still have the soil bag? Check to see if it has a time-release nutrient added. Seedlings like mild soil.

I find when you get twisty leaves, it's usually because of too much nutrient too early. Plus lots of your burns are on leaf tips. I could be mistaking some of that burn for the light burn. But I suggest that you transplant up to a slightly larger pot with a known soil (no added nutrients).

The Epsom salts may have entered into the picture. Unlikely to have a Mg deficiency so early in growth. For maintenance purposes I use 1/4 tsp Epsom salts per gallon. But your plant is too young for that.

When you add nutrients to young plants...go super easy. 1/8 strength to start and ease up as the plant grows.
JD

There's no mention on the bag of any kind of nutrients. It says only "Ingredients: Humus, Peat Moss, Pearlite, Limestone" no percentages or anything. There are slight greyish spots starting to appear on her next layer up

For the record, I only sprinkled a few grains of Epsom salt. It doesn't seem like it should be anywhere near an amount needed to kill her but I have no idea. There's also crusty white buildup on her soil. I had thought that it was surface mold at first but it doesn't look fuzzy at all. Possible build up of some mineral from my tap water?? I mean I do live on an island so possible for it to have salt in the tap water... that's probably not very good >.> I was watering her mainly with bottled water until recently.. maybe the tap water is the issue!!! So many questions...

Over the course of the next couple days, I'm going to buy some perlite and make her a nice mix in a bigger pot and water her with bottled water and see if she improves.