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Remineralization vs. chemical fertilization

Copper sulfateMy father commented to ask what's the difference between remineralization and using chemical fertilizers.  The answer is --- not much in the short term, but hopefully a lot in the long term.

Most (perhaps all?) of the minerals I've been applying are approved for organic gardening because they're mined rocks, but they're really just chemicals.  I don't believe that just because something's "natural" that it's safe for my soil, and I don't kid myself by thinking that there may not be some short-term damage to my soil microorganisms resulting from this winter's application.  I'm hopeful that by spring, though, everything will have evened out.

That's the short-term picture, but what about the long term?  The purpose of remineralization is to correct imbalances in the soil that develop over millenia of rainfall and leaching.  The theory is that if you boost levels of trace minerals that have been washed out of the earth, you can bring your soil back into balance and not have to repeat the endeavor.  (That said, it may take a few years of soil tests and remineralization to return to the optimal levels, especially since Solomon places application limits on several of the minerals, like borax.)

EarthwormIn contrast, the chemical fertilizers used in mainstream farming are generally meant to be applied before every crop, and tend to create a cycle of dependency in the soil.  For example, if you use chemical nitrogen fertilizers, the microorganisms in your soil that usually cycle nitrogen and make it available to plants perish, so you have to keep applying chemical nitrogen fertilizers.  If remineralization works correctly, it does the opposite --- you add minerals that microorganisms will keep cycling in your garden indefinitely.

Whether the theory will stand up to reality is up for debate.  I feel there's a 10% chance I'll regret spreading all these chemicals on the soil, a large chance I won't see any difference, and perhaps a 20% chance my strawberries will taste astonishingly rich this year.  Only time will tell.  (And, yes, it's all about the strawberries.)

Our chicken waterer keeps hens happy with clean water.


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The Alpha Chemicals website doesn't yield information as to the origins of the materials that they sells, at least not that I could find. But looking at the purity of e.g. the copper(II) sulfate and manganese sulfate and given that most ores need to be significantly processed to yield pure metals, I somewhat doubt that they are just "crushed rocks".

According to the Wikipedia page for copper(II) sulfate:

Copper sulfate is produced industrially by treating copper metal with hot concentrated sulfuric acid or its oxides with dilute sulfuric acid. ... The anhydrous form occurs as a rare mineral known as chalcocyanite. The hydrated copper sulfate occurs in nature as chalcanthite (pentahydrate)

And regarding manganese sulfate:

Typically, manganese ores are purified by their conversion to manganese(II) sulfate. ... In the laboratory, manganese sulfate can be made by treating manganese dioxide with sulfur dioxide. Manganese sulfate is a by-product of various industrially significant oxidations that use manganese dioxide, including the manufacture of hydroquinone and anisaldehyde.

So it seems more likely that they are synthesized. Wether this uses more resources then e.g. manufacturing synthetic fertilizer is more than I can say. I would suspect that it is on a pound-for-pound basis. But you'd probably need a lot less minerals than you would need synthetic fertilizer.

There is such a chemophobia rampant in the media that the word "chemicals" has gotten a large negative bias. There was an interesting article on slate.com about the silliness of this phenomenon.

The truth of the matter is that we are entirely made of and surrounded by "chemicals". And if they are beneficial, neutral or harmful to us depends for a large part on the dosage and how they enter our bodies. The minerals that you are now spreading on your garden contain metals that are essential for our bodies to function. But the same minerals could be extremely unpleasant and even fatal if you were to swallow a couple of grams of them.

Since the minerals you've ordered seem to dissolve quite well in water, I wonder how lasting their effect will be? Since a couple of them are extremely toxic to water-borne organisms, there is a possibility of damage to the downstream waterscape.

As for nitrogen fertilizers, if you added just as much as the soil organisms could liberate, it shouldn't poison them, should it?

On a side-note, if Mark is still into energetic stuff like explosives, Alpha Chemicals sells ready-made thermite kits, and also has the magnesium wire necessary to set it off! While it doesn't go boom, it would probably melt a nice hole in any metallic object.

Comment by Roland_Smith Sun Feb 10 13:26:53 2013

Roland --- With nitrogen fertilizers, it's complicated because nitrogen can come in a few different forms. Some require the work of microorganisms to make them available to plants and others don't. The soil ecosystem is very complex, with plants feeding microorganisms sugars in exchange for the microorganisms converting nitrogen to the form plants can use. So, if you apply the kind of fertilizer that's immediately available to plants, they cut out the middleman (the subsidies to the microorganisms), and the microorganisms tend to die out. Which is okay if you're committing to applying fertilizer at intervals thereafter, but not okay if you want the garden to be more self-sufficient (and if you don't want to lose nitrogen into the groundwater).

About runoff of the cations --- as long as you have a high cation exchange capacity and only apply enough to fill that back up, you shouldn't see problems with runoff. Nitrogen comes as an anion, though, so while it does cling to organic matter some, it doesn't cling to clay and other things that help cations stick around. As a result, it's more dicey to apply straight nitrogen than straight cations from a groundwater perspective.

Comment by anna Sun Feb 10 13:38:45 2013

Thanks for the explanation, Anna! I always learn something interesting here. :-)

It occurred to me that ammonium nitrate has nitrogen both in a ammonium cation (NH4+) and in a nitrate anion (N03-) when dissolved in water. The former (which has most of the nitrogen atoms) should stick to the soil pretty well, shouldn't it?

Comment by Roland_Smith Sun Feb 10 14:54:14 2013

Roland --- I'll bet you're right about ammonium and nitrate. I was being intentionally vague because I always forget which forms of nitrogen do what in the soil (although now that I'm starting to understand the chemistry of it better, I should refresh my memory and it might make more sense and stick.)

If we're right, ammonium would stick well in soils that have plenty of organic matter and/or clay. So, in my soil --- no problem! In sandy soil, nothing sticks very well.

Comment by anna Sun Feb 10 15:14:38 2013

Adding simple N compounds to the soil is not going to sterilize it. The bacteria that utilize ammonium, nitrite or nitrate ions do not "know" where they come from. Excess N compounds are quickly out-gassed as ammonia or nitrous oxide and not that much will actually make it to streams as run-off. The various species of microrganisms that metabolize those N types are in dynamic equilibrium and any changes you could possibly make (within reason) in their populations will quickly adjust themselves for maximum efficiency.

While I appreciate the scientific attitude & curiosity here, I think maybe an excessive importance is being placed on micro-managing the micro-nutrients.

Taking a lead from the old-time British naturalist who taught my first college bio course (got his PhD ~ 1915), he repeatedly got his point across by asking "How long is a giraffe's neck? Long Enough!"

If you're tryig to produce a commercial crop, squeezing every last corn kernal possible out of an acre, then details are important. If you're just producing for yourself, then replacing the nutrients lost in the harvest is accomplished by adding that much and a little more to allow for inefficiencies.

Like the logsitic population curve, the curve for mineral uptake/usage is ussually a sigmoid shape. You are dealing with the middle of the curve, whereas the industrial farmer is living at the top where competition is maximum. For you, even fairly large changes in micro-nutrient availability will have little effect on yield. Your goal is only to avoid the left hand side, the bottom of the curve.

Comment by doc Mon Feb 11 07:19:48 2013