[AaronT]

I can't see any reason why you can't air dry it and reuse it later. Why not try the mineralized soil while you're at it?

 

[AaronT]

Hi Stepheus and Aaron, thank you for your reply.

Regarding soil mineralization, I did think of trying it when I first read the thread a while ago. However, my understanding was that it was mainly for preventing algae. But algae was not an issue for me (probably due to the low light setup combined with plenty of floating plants).

I guess what really stopped me from trying it was that I did not fully understand how the mineralization process would affect the soil's life span. For example, I remember reading in Ms. Walstad's writing that adding CO2 will use up the soil's nutrient at a rate much faster than it is being replenished through feeding the fish (if I have mis-understood her writing, please correct me).

May be I should ask: When people maintain their tanks using Ms. Walstad's way, will the mineralization process affect the soil's life span?

Thanks.

Well, it does prevent algae in a higher lighting setup, but it's more than that. Mineralizing the soil makes a LOT more of the nutrients in the soil bioavailable to the plant's roots. It should last a lot longer than just soil by itself and can still work just fine in a low-tech setup.

 

[AaronT]

Thanks Aaron. I have two questions in mind.

When the soil is not mineralized, will the same nutrient be available at a later time?

Does the mineralization speed up the release of nutrients that would otherwise be available at a much slower pace?

Thanks.

The soil becomes mineralized when it is exposed to oxygen. Plants release oxygen into the soil via their roots when they are healthy and growing, however, it is much much faster to simply expose the wet soil to air as the oxygen needed for the process to take place is much more abundant.

It doesn't speed up or slow down the release of nutrients. It only serves to convert them to more usable forms.

 

[AaronT]

Aaron, if I understand your explanation correctly, preparing the soil through mineralization will thoroughly expose the soil to oxygen. That will result in a massive release of nutrient within a relatively short period of time. Without the mineralization preparation, much of the soil nutrients remain trapped due to the lack of oxygen. Later when plant roots release oxygen, those trapped nutrients will then be released, albeit at a much slower pace than through the mineralization preparation

However, given the limited amount of nutrients in a fixed volume of soil, the mineralization preparation will cause the soil nutrient to run out much sooner than otherwise, unless we replenish the nutrients through massive dosing. Have I missed or mis-understood something?

Thanks.

Hmm...that's not quite right.

The mineralization of the soil converts the nutrients in the soil into usable forms i.e. NH4 (ammonia) into NH3 (ammonium). That's just one example, there are many other nutrients made more readily available. The nutrients are never released during this process, only converted from one form to another.

This will serve to create a very nutrient dense soil for use in the aquarium. A mineralized soil substrate can last decades without needing to be replenished. The only limited nutrient seems to be potassium. This is true for a regular el natural style substrate too.

In short, it doesn't run out faster by releasing tons of nutrients. It instead makes tons of nutrients available to the plants for several years in a row.

 

[AaronT]

Sorry Aaron, your first explanation came across ok. Just that I was not expressing myself well. Let me try again. Hope this time will be better.

Nutrient release is a multi-step process. One of the steps depends on the availability of oxygen. Mineralization preparation speeds up (or even completed) that oxygen-dependent step by making sure that soil has been exposed to plenty of oxygen before being used in a tank.

Soil that has not been through the mineralization preparation will be constrained by the limited amount of oxygen generated by plant roots. Thus, the amount of initial nutrient release and the continued rate of nutrient release will be much less than those of the soil that had been through the mineralization preparation.

Mineralized soil does not have oxygen constraint. It can therefore release a massive amount of nutrient in a newly set-up tank and its continued rate of nutrient release high.

That's closer. I didn't mention this in the article, but the initial release of nutrients is actually pretty slow. It takes 3-4 weeks for the bacteria to establish in the substrate that help the plant's roots to unlock the nutrients from the soil. Once these microbes are in place then the plants will have a virtually unlimited supply of nutrients.

But for a given quantity of nutrient, the more rapid it is being released, the sooner the nutrient will be completely depleted.

One way of replenishing nutrient is through fish food. But if the soil nutrient release is at a much faster rate than that of the replenishment from fish food, soil nutrient will run out. And that is my concern with the impact of mineralization preparation.

The nutrients are never released anywhere, rather they are unlocked and use by the plant's roots as needed. For example, if I were to measure the nitrate and phosphate levels in my tanks they would be nearly zero almost all of the time because the nutrients stay in the substrate.

The mineralized soil will not run out of nutrients for many many years. That's actually the whole idea behind it. Sean, the fellow who first introduced me to the idea has had tanks running on the same substrate with only very minimal potassium dosing for 15 years now.