PLS HELP ME yellow leafs

Hi, my first grow outdoor
2 weeks ago I noticed that the lower leaves were turning yellow,
the top leaves are healthy
At first I told myself that this is just the death of old leaves but more and more leaves are yellow.It doesn’t look like a typical nitrogen deficiency but rather something else. Any tips I hear guys, help

Land: earthworm humus and smooth forest
soil.
Water: tap water (I can't measure pH) but so 7
Nutriens: volldünger linz (NPK: 14-7-21) twice a week get 1 gram per liter of water

I am not familiar with that nutrient line, but those NPK numbers are very high, and a gram per L is A LOT of anything. I would stop feeding them anything for at least a week, just water and I bet things improve. There are probably so many salts in the soil the plants nutrients uptake is not working properly.

Thanks bro

do you have drainage?