1 Cup Epsom Salts Per Plant - REALLY??

[lakelady]

Raybo, thanks for forging ahead as our own little TV Mythbuster Always good to see from live experience if something really works, or if it's just bunk.

[Dewayne mater]

Just to be clear, when I mentioned "manipulating the environment" that was directed solely at the fact that an earthtainer is a closed system that doesn't use soil, but a growing medium where pretty much nothing goes in except what you put into it. That is different than growing the ground where many non controllable factors come into play.

I'm just a student of this hobby and have no idea if the doses in question are insane or merely maximum useful amounts, so I have no judgment towards doing this or not at this point. Hopefully, with trials like this one and perhaps others, we will learn if this is another arrow in our quiver or not. Looking forward to the results.

Dewayne.

[dustdevil]

Ray,

Thanks for clarifying what epsom salts you are using. The photos of the bag say it all. This is an important post and I'm glad you are sharing your findings. Keep up the good work!

Dust

[rnewste]

Originally Posted by dustdevil

Ray,

Thanks for clarifying what epsom salts you are using. The photos of the bag say it all. This is an important post and I'm glad you are sharing your findings. Keep up the good work!

Dust

Dust,

What I find as "serendipity" is the coincidence that what Bingster came up with (1 cup per plant) and the sum of 50 Teaspoons top applied to in-ground tomato plants which is essentially the same total amount, is amazing.

Think about the commercial EarthBox where you are instructed to include 2 cups of Dolomite Lime in the 1.6 cubic feet of Potting Mix when planting. One would NEVER apply 2 cups of Lime when digging a planting hole in a raised bed, for example, yet the "chemistry" and osmosis properties of SWCs seems to thrive on this amount of Lime.

Kind of reminds one of the Ronco rotary cooker where you are extolled to: "Set It - - And Forget It"!!

Raybo

[dustdevil]

Ray,

Serendipity? In your case, I think it is the subliminal messages you have been receiving from the mothership through the skylight while you sleep at night

Dust

[swamper]

Originally Posted by fortyonenorth

As Dewayne pointed out above, the Earthtainer is a closed system - there is no run-off. So, any sulfates would be retained within the reservoir and available to be wicked-up into the growing medium.

Thanks for pointing that out 41, but de wayne didnt mention, that it is a closed system and that water doesnt drain out.

It's definitely not a safe assumption that the same soil chemical dynamics would apply in a field; there's no use to calculate lbs/acre and try to duplicate in real soil unless you have VERY high organic carbon content in your soil. The most significant factor in the containers is the high percentage of organic matter which no doubt makes the plants hungry for Mg. I still dont buy it that SURPLUS Mg is the reason why they grow fast. Absence/scarcity of Mg would no doubt limit growth, and is a very common problem for container growers using organic mixes. The reason they grow so fast and healthy is is NPK, soil moisture, and soil oxygen that these containers provide.

[fortyonenorth]

I agree that we're talking about a unique environment. The exchange capacity is likely in the 20-30 range which would give the soil mix a large capacity for adsorbing nutrients. Still, I've always thought that the Ca:Mg ratio is extremely important. I don't know how quickly the Mag sulfate will become available, but I know the rule of thumb for dolomite lime is complete breakdown over three years - that means only 1/3 availability during the first season. So, the Ca:Mg ratio is likely to be somewhat inverted.

Originally Posted by swamper

Thanks for pointing that out 41, but de wayne didnt mention, that it is a closed system and that water doesnt drain out.

It's definitely not a safe assumption that the same soil chemical dynamics would apply in a field; there's no use to calculate lbs/acre and try to duplicate in real soil unless you have VERY high organic carbon content in your soil. The most significant factor in the containers is the high percentage of organic matter which no doubt makes the plants hungry for Mg. I still dont buy it that SURPLUS Mg is the reason why they grow fast. Absence/scarcity of Mg would no doubt limit growth, and is a very common problem for container growers using organic mixes. The reason they grow so fast and healthy is is NPK, soil moisture, and soil oxygen that these containers provide.

[RayR]

Here's an interesting read on Magnesium in the Soil. There maybe some clues here as to what is going on in the 'Tainer mix.

From the info in the article I think what we can discount is the idea of Mg toxicity from the combination of all that Epsom Salts and the Dolomite. It doesn't seem to be a real concern, with plants like Tomatoes anyway. The plants would take up available Mg to the maximum they can hold in the tissues and that would be the end of it until they need more. I agree with swamper that surplus Mg is not going to make the plant grow faster.

I don't know what the CEC (Cation Exchange Capacity) of the mix is, but if it's high it could be holding quite a bit of Mg in reserve, which is unavailable to the plant as well.
Ca and K in sufficient quantities in the mix may be a limiting factor on Mg availability and uptake also.
There may be some other plausible things going on chemically.

[Dutch]

Originally Posted by swamper

The most significant factor in the containers is the high percentage of organic matter which no doubt makes the plants hungry for Mg. I still dont buy it that SURPLUS Mg is the reason why they grow fast. Absence/scarcity of Mg would no doubt limit growth, and is a very common problem for container growers using organic mixes. The reason they grow so fast and healthy is is NPK, soil moisture, and soil oxygen that these containers provide.

Swamper, you have made several statements about soil. Are you aware that Raybo uses a soilless mix? There are no organics such as humus matter in his containers. This is just a point for clarification.
Dutch
P.S. Bingster also uses a soilless mix (straight miracle-gro).

[fortyonenorth]

Dutch - I don't grow in Earthtainers, but I assume the mix consists of a large proportion of peat for moisture retention and wicking purposes. A high peat content will make the % organic matter high as well. I assume Swamper's simply using "soil" as a generic term for the planting medium.

Originally Posted by Dutch

Swamper, you have made several statements about soil. Are you aware that Raybo uses a soilless mix? There are no organics such as humus matter in his containers. This is just a point for clarification.
Dutch
P.S. Bingster also uses a soilless mix (straight miracle-gro).

[rnewste]

Geez,

I learn so much on this Forum. You guys must have REALLY paid attention in Chemistry Class - - while I was out chasing "skirts".

Thanks for the chemistry viewpoints as to what is really going on in the SWC with these supplements.

Raybo

[RayR]

Raybo, I only have two vivid memories of Chemistry class, one where our dorky teacher cut a piece of pure Sodium and put in a beaker of water and it blew up in his face and another of that "skirt" that sat next to me in class.
Who would have thought that I would be learning something about soil chemistry later in life to practice a vegetable growing hobby.
I think the more you read from the experts on soil chemistry and soil biology, for all the things that are known to be true there's far more that they still don't exactly understand.

[tomakers]

Originally Posted by RayR

Raybo, I only have two vivid memories of Chemistry class, one where our dorky teacher cut a piece of pure Sodium and put in a beaker of water and it blew up in his face and another of that "skirt" that sat next to me in class.
Who would have thought that I would be learning something about soil chemistry later in life to practice a vegetable growing hobby.
I think the more you read from the experts on soil chemistry and soil biology, for all the things that are known to be true there's far more that they still don't exactly understand.

I always found it was more productive to help the "skirts" with their chemistry homework.

[maf]

For those who would like some more reading on the subject, here is a link to Dr. Linda Chalker-Scott's take on Epsom Salts:
Horticultural Myths Files - Epsom Salts

The bottom line is that adding Epsom Salts is only beneficial if there is a magnesium deficiency in the first place, and adding any extra beyond the levels needed to correct the deficiency is wasteful, and can (potentially) cause problems like those mentioned previously in this thread.

Magnesium deficiency in container grown tomatoes is a common problem, so an experiment like this, which does seem excessive in the quantity used, will nevertheless provide some interesting results. It would be very interesting to see how a control Earthtainer with a much lower dose, say a teaspoon of Epsom salts per week added to the reservoir, would compare.

[rnewste]

maf,

Thanks for the link to the Article. It is a good read.

The Article focuses entirely on in-ground growing situations, which is understandable. In a SWC which uses a soiless combination of peat, microbark, and perlite, I wonder if the Author's conclusions would be valid.

In any event, to your suggestion I have just started 3 CeleryTainers; one with 1/2 cup Epsom Salts, one using 1 cup, and the third one with 2 cups Epsom Salts. Everything else (Mix, fertilizer, dolomite lime) is identical in all 3. I'll document how each performs over the next 100 days until harvest.



Raybo