Is my soil magnesium deficient?

Timmo

Well-Known Member
My mix:

30 gal base (equal parts peat, perlite, and compost)
3/4 c soil sweetener
9 c EWC
1 c bat guano
1 c fish bone meal
2 Tbsp Ful-Humix
2 c Azomite
2 c basalt dust
2 c kelp meal
2 c alfalfa meal
2 c crab meal
2 c neem seed meal
1 c mycos
3/4 c yucca powder
2 c diatomaceous earth

The soil sweetener is dolomite lime. The label says that it's 82.25% calcium carbonate and 4.82% magnesium carbonate. My plants seem to be doing fine (although lots of them have red stripes on the stems), but I haven't taken anything to harvest in this mix yet. So far, I've used the soil without letting it cook, but I'm getting ready to mix a big batch that will sit for a month or more. It's my understanding that dolomite lime doesn't doesn't become available very quickly. Am I getting enough mag via the other amendments? Should I add epsom salt to the mix?
 
With all this stuff it's definitely not mg deficient but might be unbalanced in the long run.
 
I think there's way too much NPK as well as uncontrolled content of micronutrients.
 
Leave only 30 gal base (equal parts peat, perlite, and compost), 9 c EWC, 2 c basalt dust, 2 c crab meal and 1 c mycos.
 
I use SubCool's supersoil mix... which includes a few things that you didn't. The secret though, as you are figuring out, is to let that soil cook for a long time. My soil is now over a year old, and gets better with each grow. I also re-supplement the soil with veg and flowering spikes of raw materials, so I really don't add anything extra to the compost pile. Here is the recipe that I use:

1 large bag of a high-quality organic potting soil with coco fiber (or perlite) and mycorrhizae (I use roots organic)
3.125 to 6.25 lbs of organic worm castings
.625 lbs or 5/8 lbs or 10 ounces steamed bone meal
.625 lbs or 5/8 lbs or 10 ounces high P bat guano
.625 lbs or 5/8 lbs or 10 ounces blood meal
3/8 lbs or 6 ounces rock phosphate
3/32 cup or 1.5 tablespoons Epsom Salts
1/16 cup or 1 tablespoon sweet lime (dolomite)
1/16 cup or 1 tablespoon azomite (trace elements)
3/4 teaspoon powdered humic acid

Your kelp and alfalfa meals might end up breaking down and supplying nitrogen at the wrong point in the grow... probably best to save their use for compost teas at the appropriate times. All of this stuff will continue to be available for a long time in a living soil. I am now even going as far as using a no-till method in flower, and half of my plants are now sitting in the very same soil that the plants before them sat in, roots and all... and they are thriving! I can not tell the difference in my tent from the plant put in fresh cooked soil, and the no-till.
 
another note regarding magnesium:

I use molasses very liberally throughout the garden. All of my natural organic fertilizers are made and stabilized with large amounts of molasses. I use a liberal amount of molasses in my compost teas. Even my cal-phos supplement, is fortified with molasses to stabilize it and provide more trace minerals.

There is a good percentage of magnesium in molasses. More long term magnesium is also mixed into my soil with the dolomite and the epsom salt where it can break down over time, but the lion's share of the magnesium that my plants get has to come from all the molasses that I use. Molasses is my secret weapon... and I strongly recommend its steady use throughout the grow... at least until the last two weeks, when it is time to start cleaning up the plant and the soil.
 
Your kelp and alfalfa meals might end up breaking down and supplying nitrogen at the wrong point in the grow...

Would it alter your concern if I told you I'm growing outside with a long vegging period?

On a related note, I've got three different strains (Mastodon, White Widow, and Northern Lights) vegging in the same soil that are all showing these symptoms:

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Any thoughts on what's happening here?
 
it does appear to be magnesium, but it appears that they might be hungry for macronutrients too. Is all of the yellowing at the bottom, or has some of this browning at the leaf tips happening at mid level too? If you see it mid level, sort of skipping around, it does suggest that magnesium is the major problem, but it could be too that out there in the strong sunshine they just need some extra feeding once a week or so, and this will continue to progress upward gradually if this is what is going on.
 
Would it alter your concern if I told you I'm growing outside with a long vegging period?

A little... but the problem is timing... the long veg period will use some of it, but most of the alfalfa is slow release and will break down about mid flower and start adding a lot of N to the soil, not really helping things a lot at that point in the grow. If instead it was applied after bubbling in a compost tea, a large part of that goodness is water soluble and can provide an immediate benefit in veg. No harm done though, for all that N that is left over will be available for the next grow... just be careful not to make the next round too hot by adding a lot more N to the soil... you are probably good in that department for a while. :)
 
quick fix. add two teaspoons, per gallon of water, and water in well. i use epsom salt. its pure mg. it is a wonder tonic. i also, add some to my semi regular waterings. plants use alot of mg. and, to be quit honest, all this "organics" bla bla . is just that. a plant cannot use the organics, until they are all well composted. bottled nutes, are allready broken down. and readily available to the plant. dont think of them as "chemicals". an old label, for days long gone. when things like ddt were used. nowadays, noone can even manufacture true nastys. anytime i have had real problems with grouth, is when i used organics. for instance. i have been using nothing but alaskan fish, for my outdoor. the plants are "ok". but, are quite pale. yesterday, i put my foot down, and mixed up some nutriculture 20-20-20. talk about green green green. and vibrant plants. in one day. happy girls. now, they will actually make their size. imagine that.
 
Magnesium as all imobile nutrients won't show as bottom deficienfies but as top ones. What you have though is not nitrogen or phosphorus def but most likely lockout or nute burn.
 
Magnesium as all imobile nutrients won't show as bottom deficienfies but as top ones. What you have though is not nitrogen or phosphorus def but most likely lockout or nute burn.
magnesium is the funny one... it can and oftentimes does first present as a mobile element deficiency in the bottom 4 fan leaves, and then quickly moves to all over the plant. Immobile deficiencies almost always show up at the very top, in the new growth. Magnesium appears to have a limited mobility, the only element that acts like this in our plants.
 
emilya molasses is my secret weapon too i make a foliar that if went to market would make me a billionaire and molases is a key ingredient also doubling as a chelator and it raisesyour brix
 
Canni, I'm not quite ready to ditch organics, but thanks for the advice, and I'll give the epsom salts a try.

Emilya, it started at the bottom and has progressed to the middle. I'll step the molasses, and I'll try feeding more.

Conrad, I've got 10 plants doing this, so I've you have a different remedy to suggest, I'd be happy to do some side-by-side testing.

Photos, care to share that foliar recipe? :adore:
 
My guess is you went supersoil way which means you pushed all nutrients through the roof especially potassium and nitrogen. Also you might have whacked out calcium to magnesium ratio which brings a lot of problems as one locks out another usually if not kept within the range. And no molasses doesn't raise Brix cause it contains too much potassium, it's a stupi thing to say. It also clogs the soil. But if you want to keep doing more damage go for it.
 
My guess is you went supersoil way which means you pushed all nutrients through the roof especially potassium and nitrogen. Also you might have whacked out calcium to magnesium ratio which brings a lot of problems as one locks out another usually if not kept within the range. And no molasses doesn't raise Brix cause it contains too much potassium, it's a stupi thing to say. It also clogs the soil. But if you want to keep doing more damage go for it.

I went supersoil over a year ago and it was the best thing that I ever did. I hardly think that I overused the nutrients, as my soil keeps getting better and better over time, and of course no one would consider 1 tablespoon of epsom salt in an entire bag of soil, overdoing it. The mix seems quite effective to me, as i have been reusing the same soil over and over again for over a year now and despite what you say, with bottle after bottle of molasses thrown into the mix... my soil has not clogged once. When does the damage start?
 
The problem with supersoil approach is that it's unreliable. What I mean is one grower will find it great, and another one will start having problems very quickly. There's no way to establish how plant will react for it cause there are so many breeding programs out there, and so many varieties popping up with very different nutrient needs. Also there is no one supersoil, recipes are usually as creative as growers get. Some will add an excess of phosphorus and potassium while other ones will push the nitrogen. It's easy to undercook your soil too, which means plants will have to deal with it as soon as they're planted in the mix, and with many nutrients locking out each other I wish good luck to those who want to figure out why this strange wilting or burning happens when it's all organic. Yes it's organic, but it's a steroid approach without any deeper thought to it. I also used molasses twice and didn't see any positive effects. Bacteria will eat the sugar and then what? How can a plant possibly benefit from it?
 
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