Anyone run into problems with toxicity from excess epsom salt? In other words, excess amounts of sulphur or magnesium? Any idea of the symptoms with either element in toxic amounts? I have plants 2 weeks into flower and they have been showing nitrogen deficiency, which ain't actually correct due to the significant levels of nitrogen present in my nute program. Basically my lower fan leaves were yellowing uniformly at a rapid rate. Two suspicions here, one is sulphur/magnesium toxicity or iron deficiency from too much phosphorus with using PK13/14. Thanks
To me it sounds like you have some sort of lock-out due to high salts in the soil. But thats only a guess from the information provided.When in doubt Flush Flush Flush. Thats IMO. Good luck though
whats ur pH? there may be mineral salts present in ur medium, but if the pH is off then the plant is unable to absorb them, these salts will build up in ur medium and cause a toxicity, also a pH lock out will cause deficiencies
^ Yes of course I know that it's due to salt buildup and ph is spot on at 5.8 given that I grow in coco and have already flushed which has corrected the issue. Though that's beside the point, I'm trying to figure out which nutrient is being antagonized and which nutrient in excess is causing this in the first place. It's a pain in the ass to flush every time there is an issue, better to learn what actually is happening to prevent it I say. Thanks!
I agree that pH is the first place to look and you probably will want to flush to re-set to fix the problem. You could be getting some nute lock-out if your pH is out of range, but also possible that isn't talked about as much is that nutes can lock each other out -- an excess of one means a lock-out of one or more others. Too much Mg shouldn't be locking out N (Calcium usually is what Mg locks out first), so maybe you really don't have an N def, or maybe it's whacked from something else. Usually a good test is this: if you think a nute is deficient so you add more and it just keeps on looking deficient and so you add more, and so on, then the amount of nutes you're giving isn't the problem, the nute is locked out somehow. Stop pushing nutes, test pH, develop a plan based on that pH reading and flush to get started back on track.
^ I certainly have all the fundamentals covered. There could be a few issues with PH spikes with using phosphoric acid, it doesn't seem to be very stable. If adjusted to 5.8, then come back a few hours later and the ph jumps up to 6.1-6.2, readjust it back to 5.8, then it still difts upwards over time. But coco is rather forgiving with PH, Mred has run his at low 5's and low 6's without any noticeable difference. The second issue is simply the amout of phosphorus, which will further aggravate a phosphorus toxicity problem. Given the unusual nature of how my lower leaves yellowed and dropped off within 2 light cycles without any signs of burn, drying out, curling or any imperfections other than uniform yellowing. Makes me think this may be a micro nutrient lockout and from all the information and pictures I've seen, iron seems to be the one that fits and phosphorus lockouts iron. Another point worth mentioning, is not to take the labeled nutrient instructions for granded. Even though im running Canna coco nutes, I believe they reccomend far too much. I was allowing 20%+ runoff at each water/feed, yet still ran into salt buildup issues. Still there is the chance of excess sulphur and no one seems to know how this effects the plant?