# Soils: Organic v. Fertilized with Chemicals



## dwalstad (Apr 14, 2006)

In the past, I recommended organic, non-fertilized soils (e.g., Miracle Gro Organic Choice or MGOC). The soil was readily available and worked well for me.

However, I'd like to reconsider that recommendation. An experiment I did recently comparing soil covers (STS v. sand) prompted me to purchase a fresh potting soil. The one I chose was not organic; it contained chemical fertilizers. Would the soil work in a submerged situation? Turned out it worked just fine.

I used the Walmart Potting Soil ($3.93 for 8 qts) shown in photo. Main virtue was low price and low nitrogen. NPK (0.023, 0.03, 0.06). I ignored the fact that it contained perlite balls. The chemical fertilizers were advertised as "slow release." That seems to be true at almost 2 weeks after setup, I'm measured no nitrites or ammonia in water in either bowl. pH and GH are stable, no humus release.

Plants seem to be doing okay. Photo of bowls two days after setup and then again at 12 days. Bowl on right has STS/sand cap, the other pure sand cap. (I added a little sand to STS cap to better hold plants down, as STS clay is awfully light.)

Here's more details about this soil:

Composed of compost, forest products, Sphagnum peat moss and perlite. Chemical fertilizers are ammonium phosphate, ammonium nitrate, potassium nitrate, potassium sulfate, calcium phosphate. Chemicals were polymer-coated so that they would release slowly. Overall, the soil was one of relatively low fertility; the NPK ratio was only 0.023, 0.03, 0.06. [In contrast, the MGOC (Miracle Gro Organic Choice) that I used successfully for my shrimp bowls several years ago had an NPK of 0.10, 0.05, 0.05.]

Apparently, there are standards for potting soils in some states, such as North Carolina. Thus, manufacturers can't throw just anything into the bag.

http://www.aapfco.org/state_laws_regs.html

Bottom Line: Many brands of potting soils will work. If I had one simple gauge I would keep my eye on, it would be the nitrogen content. One organic potting soil (NPK= 1.1%, 0.3%, and 0.35%) that I've been using for outdoor plants has an N of over 1%. It's releasing a LOT of ammonia into water in some bottle tests. Note it has 47 times more nitrogen than my new fertilized potting soil. That is, 1.1% ÷ 0.023 = 47. Fortunately, I didn't use this in my tanks!


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## hoppycalif (Apr 7, 2005)

Is there any benefit at all for perlite in an aquarium substrate? I tried a soil many years ago, before I had any idea what I was doing, and it was such a disaster as the little balls floated everywhere, and seemed to have a never ending supply. So, I promised myself I would never, ever do that again.


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## mistergreen (Mar 3, 2007)

I had left over soil with perlite and used it in the aquarium. lol, it'll float, just scoop it out. It's no big deal. I'm sure some of it is still in the soil.


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## dwalstad (Apr 14, 2006)

hoppycalif said:


> Is there any benefit at all for perlite in an aquarium substrate? I tried a soil many years ago, before I had any idea what I was doing, and it was such a disaster as the little balls floated everywhere, and seemed to have a never ending supply. So, I promised myself I would never, ever do that again.


I'm glad you didn't give up on soil! 

I was surprised to learn that Perlite is a type of light-weight glass, not a plastic. It is filled with air pockets. For terrestrial plants, it prevents soil compaction and acts as a reservoir of air/oxygen preventing anaerobic conditions.

In the aquarium, I can't imagine that it would hurt that much.

Many potting soils have perlite. An excessive amount of perlite in some could cause the disaster Mistergreen experienced. That said, I wouldn't veto potting soil because of perlite. If you look at the dry potting soil in my picture, you only see a few tiny (2 mm) white perlite balls. They weren't-- and aren't-- a problem.


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## hoppycalif (Apr 7, 2005)

I can't find the Walmart Potting Soil you used, but I did find Miracle Gro Seed Starting Potting Mix, which has 0.03, 0.03, 0.03 fertilizing. That should work fine, right? But, I also thought all of Miracle Gro potting mixes contain water holding blobs of polymers. This one doesn't seem to have that feature.


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## mistergreen (Mar 3, 2007)

The seed start mix is mostly peat moss, it looks like from my end. Not sure if that's a good thing or not.


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## hoppycalif (Apr 7, 2005)

mistergreen said:


> The seed start mix is mostly peat moss, it looks like from my end. Not sure if that's a good thing or not.


It is high on peat moss, as are many or most of Miracle Gro potting mixes. I haven't found a mix that isn't high on peat moss, but contains limited, but complete fertilizers in it.


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## mistergreen (Mar 3, 2007)

Potting soil has composted organics (dirt) in it and cheaper. Potting mix is mostly peat and or coco coir to make it fluffy. The nutrients are are added in.


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## hoppycalif (Apr 7, 2005)

How about Black Gold Garden Soil: http://www.sungro.com/retail-product/black-gold-garden-soil-0-05-0-02-0-05/ which has Pearlite in it, and possibly vermiculite? The amount of nutrients is about right, and the cost, at Ace Hardware, is about right.

I'm thinking one way to get rid of vermiculite is to "wash" it to float the vermiculite to the surface to be dipped out with a net.


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## dwalstad (Apr 14, 2006)

I see no reason why this wouldn't work just fine.


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## hoppycalif (Apr 7, 2005)

dwalstad said:


> I see no reason why this wouldn't work just fine.


Thank you Diana!! Now I should buy a bag before they stop selling it.


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## Michael (Jul 20, 2010)

My choice would be the Black Gold, then do a few soak and drain cycles. That will get rid of most of the perlite, tannins, and any excess nutrients.


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## dwalstad (Apr 14, 2006)

The selected soil has fairly low fertility, as suggested by only 0.05% nitrogen. That's half that of the MGOC that I used successfully in the past with no presoaking, washing, mineralization, etc. 

Presoaking and washing may only wash away the nutrients that plants could enjoy. It makes the setup process more lengthy and tedious. Here, I trust that hoppycalif has a decent variety of fast-growing plants that can take advantage of his chosen soil.


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## hoppycalif (Apr 7, 2005)

dwalstad said:


> The selected soil has fairly low fertility, as suggested by only 0.05% nitrogen. That's half that of the MGOC that I used successfully in the past with no presoaking, washing, mineralization, etc.
> 
> Presoaking and washing may only wash away the nutrients that plants could enjoy. It makes the setup process more lengthy and tedious. Here, I trust that hoppycalif has a decent variety of fast-growing plants that can take advantage of a his chosen soil.


I can live with the pearlite, and I'm getting much more appreciative of low work as I get older, so no washing or soaking! By the time I start setting this up I will have enough plants ready to go. I'm still thinking about which plants.


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## Michael (Jul 20, 2010)

Hoppy and Diana, I'm sorry but perlite gives me the creeps!


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## Am2020 (Sep 10, 2019)

Michael said:


> Hoppy and Diana, I'm sorry but perlite gives me the creeps!


Had a coworker that couldn't touch that stuff and also couldn't touch styrofoam. Both gave him chills down his back. He described it as the same as hearing nails on a chalkboard. Do schools still have chalk boards?


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## hoppycalif (Apr 7, 2005)

Am2020 said:


> Had a coworker that couldn't touch that stuff and also couldn't touch styrofoam. Both gave him chills down his back. He described it as the same as hearing nails on a chalkboard. Do schools still have chalk boards?


None of the schooling fish I have had had any chalk boards.


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