Yellowing of lower leaves and crispy

https://www.growweedeasy.com/cannabis-plant-problems/nitrogen-deficiency

Nitrogen is dangerous low

@autoflower i have some calmag ordered, should arrive before next feed 👍 thats bang on what happened, week 4 blues. Haha i have realised the errors of autos and have some photos arriving that I'm going to clone off and switching grow to a SOG. 24 in 1 litres in the 2x2 space Thanks for the advice

Add calmag if you don't already. It comes with a little bit of nitrogen. The bottom leaves that uniformly turn yellow and brown up and curl on the ends is a classic nitrogen deficiency characteristic. The other leaves with yellow tissue with green veins could be magnesium deficient. Magnesium is responsible for chloraphyl production which is what makes them green. And of course, calcium is in calmag which is why most people use it, because of the demand for it in Coco Coir. Not saying your plant looks calcium deficient, but adding some cal mag wouldn't hurt if you aren't already. Some people aren't big fans of mid grow flushing. I am however and i suggest to anyone that you should flush your soil before you feed week 3 or 4 of your nutrient regiment. If you look around this website you'll find a clear pattern around week 3 or 4 of flower where shit starts sliding sideways and plants start showing issues, usually from toxic soil which can cause lock out of certain elements. If you flush out all that salt thats built up over veg and into the first few weeks of flower, then you'll likely have a smooth sail to the finish. And stop growing auto's indoors. Have a little self respect!

I have flushed and took readings. Watered 1.5 litres at 6.5ph Plant 1 2 3 Weight BF 3.1 3.1 2.8kg After 1.5 Ltr 3.9. 4. 3.6kg Runoff PH. 6.3. 6.3. 6.3 C (161). 470. 818. 971 EC (335). 941. 636 942 I have also filled the soil around the edges to retain the water better. Going to do another flush today 👍

@angus thank you so much for the detailed answer, really appreciated. Will get right on it hopefully not too much damage has been done but definitely been under watered until now 😅