I actually rarely see low in the leaf ever so I need to isolate this , is it from soil or applied k

I’ve used foliar k in the past but I need Mg and the two aren’t compatible in a foliar. Well you can mix but use quickly

I don’t see deficiency in calcium either as I rotate Finely Ground calcium lime Across farm That is visually highly available . But available calcium is important and will try some granular calcium sulphate

I will try some Kieserite Too as I’ve had good responses but it is expensive

I’m considering Sulphate of potash at lower rate on Oilseed rape and Some cereals

I really need to see where k is more in ideal range is Mg available

If it Is then few crops won’t be long dragging down k to a more desirable level if I don’t spread any

If Mg is still not available when k is ideal then I need to apply it

Pretty simple, I need to be applying Epsom salts with everything in reality