The ultimate clay-based substrate thread

preparing terrarium soil

I have been meaning to post my soil recipes for a while now. On Monday I will have some exact numbers, pictures, ideas and recommendations.

For now I just want to touch on a couple things that have been said already. The soil benefits the frogs not only through calcium but a better balance and delivery of nutrients to the frogs. The key to getting it to be a success is for the soil arthropods to survive in the soil. For this to occur you need a reasonable depth of soil that is not waterlogged or compacted. The soil arthropods will live, eat, and breed in the pores of the soil where they are safe from frogs. Inevitably, and hopefully, they will wander out of the soil and a portion of their population will become frog food.

Although most of the tropics is covered in red-orange soil this is not essential for a healthy arthropod population. In fact temperate soils of clay/silt origin are much more enriched in all nutrients (except nitrogen). Furthermore I have been to parts of the tropics that are covered in very nutrient rich soils that are of volcanic origin, these soils are black.

For those of you in the southwest United states (and even through Maryland) you have access to Ultisols, a red/orange soil that is similar to tropical soils.

The key steps to being successful is getting soil aggregates that do not break down despite repeated wetting/raining from misting systems.

My experimental IAD soil tank is doing well and the soil is not having its aggregates break down. the pore spaces are maintaining and you can see organisms moving in these spaces.

In my next posts I will go over some of the ways I have found to do this and will try to have some soil available at Frog Day

soil recipe part 1

As promised (although late) here is my soil recipe(s). These are not yet thoroughly tested so please use at your own risk.

Right now I have 2 methods for getting soil into my tanks. The first method involves getting local soil and changing it both by amending it and by applying physical processes.
The IAD display tank and the Lorenzo tinctorius tank I set up last night were made this way.

The IAD tank and the Lorenzo had their soil made in the same way but were set up differently.
The main soils for each of these tanks was composed by starting with local soil, preferably of high clay/silt content and low sand content (this may be difficult for some of you to obtain depending on your location). For the IAD tank I started with a red/orange clay from Staten Island (not sure of the soil type), for the Lorenzo tank I started with soil from my Garden in Ithaca (grayish glacial till soil). It is a composed of Loess (a combination of silt/clay). For both soils I pushed them through a 2 mm screen, it is actually a screen lid from a fish tank (not the fine mesh, the next size up). This is best done when the soil still has moisture but is not wet or really dry. The soil should crumble in your hand when you apply force to it, not deform, and not crack and get powdery. You should form little aggregates in your hand (to me one of the sexiest states a soil can be in).

After I did this I discarded all of the rocks, roots, and gravel that did not pass through the sieve. I then mixed in some iron oxides (lets say ~1 TBSP per quart/liter of soil). For the Lorenzo tank I used black iron oxide, for the IAD tank I used red and yellow iron oxides.
Then I sprayed the soil down enough just enough to get it to clump up again. The oxides should be “activated” by the water and get more intense in color and wet/sticky. Mix around the soil until it is uniform. Do it gently, it doesn’t have to be completely homogeneous. Let it sit out and dry until it is crumbly again as mentioned above. Pass this soil through the sieve again. You now have a local soil augmented with iron oxides.
From here on I will describe what I did for each tank separately:

The IAD tank has a soil layer 6.5 cm (2.5 inches) thick. The tank has a false bottom made of eggcrate panel, covered by 7-mesh, then by fine nylon screen, and finally a layer of brown paper towels (which I am sure has rotted out by now). The paper towels prevent the soil from washing through the screen before it has had a chance to settle and develop some structure. The first layer over the towels was a layer of reddish sand (any sand will do) ~1 cm thick. This was then covered by a layer of the soil made earlier, 5.5 cm thick. It was just poured in and moved around lightly with out any hard packing. I put in the plants (mostly just roots and whatever soil they held from the original pot), wood pieces, and logs. I covered the soil with crushed up oak leaves, and then slowly wet the soil by spraying it with a spray bottle. It takes a while but is necessary to wet the soil without causing it to break (similar to gentle rain). The oak leaf pieces protect the soil from the impact of the water and facilitate its infiltration. I add enough water until the false bottom has about 5-10 mm of water in it.
I added 6 neonate canal zone auratus froglets to his tank 2 months after its creation and seeding with springtails. I routinely add kitchen scraps (veggie pieces) and never feed it with flies. The frogs reached full size in less than 3 months! I am not sure if it is due to the arthropod fauna, soil, or both.

The Lorenzo tank is 10 gallons (standard). The soil is 3.6 cm thick composed of 3 layers. The first layer (over the paper towel) is a layer of perlite that was crushed and passed through a 2 mm mesh and then mixed with some soil and iron oxide (1.2 cm thick). The second layer is a mix of 50% augmented soil and 50% ironed perlite (1.2 cm thick) the last layer is just the iron augmented soil (1.2 cm thick). I then covered it with leaves and logs and watered it as mentioned above. This time I also added Styrofoam packing peanuts under the false bottom to act as a surface for biofilm formation to aid in nutrient cycling.
The Lorenzo pair laid eggs within 24 hours of being in this tank!

http://www.frognet.org/gallery/album41

any questions or anything I left out?

The second method is to fabricate a soil from pure ingredients from a pottery company. I have made some soil this way but have yet to “put it to the test” in a tank. Worthy of note though is that the IAD tank did contain a small amount of soil made this way and it looks indistinguishable from the amended soil even after almost 5 months. (will write more on this in the next post)

Recipe 2

sorry for the delay. I had the recipe in my Lab (where I make the soil) and kept forgetting to bring it home where I write my frog emails.

This soil recipe makes soils from "scratch," all ingredients you can get from a grocery store and local pottery supply.

here is the general recipe in grams of ingredients and percentages:

kaolinite (EPK) 1100 [58%]
Bentonite (kitty litter) 550 [29%]
Fe Oxide red 70 [4%]
Fe Oxide Yellow 70 [4%]
Al oxide 60 [3%]
sugar 9 [.5%]
cornstarch 9 [.5%]
gelatin 10 [.25%]
soy protein 10 [.25%]
CaCO3 20 [1%]

This recipe is just based on the soil composition from my study site in Panama. Other recipes will work, that mimic other soils.

Mix it all together with enough water boiling water to make it like yogurt. Mix very well (egg beater, potato masher, etc) Heat it up in the oven to lightly boiling/bubbling
(be careful it bubbles ans it burns when one pops and lands on you)
you will have a soil type smell in your kitchen from this
mix it up one more time, allow to cool, then allow it to dry.

It should be dry enough to crumble apart with some force but not hard enough to to require a hammer or make dust.

Pass it through a fine screen (usual reptile screen ~1 mm).
Take your soil and put it in a container so you can compact it again (yes I know this seems redundant)
At this point you are now compacting all the small pieces into larger pieces that are loosely bound together. You can use a lot of force, like your foot or your body.
Take the soil out and it should still com apart fairly easily (if your soil was too wet when you started it may just be a big clay lump at this point)
break it apart again and pass it through a larger screen ~2-3 mm.

These small soil balls should now be ready for a frog tank. For variety you could skip the fine screen for some of the soil and just go to the large screen. It would just give you larger tight clay aggregates (harder for roots to penetrate, but still hold water and nutrients at their surface)

any questions?

Matthew Mirabello
Ithaca, NY

Edit - ingredient added to recipe - Oz 1/6/08

EDITTED! (more calcium than I thought)

The water should not matter. any hardness will be nothing in comparison to the ions in the soil. Unless you suspect your water has high levels of organic contaminants or heavy metals I would not worry about it. (and if your tap water is that bad.... hopefully you are not drinking it)

More calcium is not bad, within reason. Even the amount I prescribed may be enough to buffer it at a higher pH, I added .4% Ca

The soils I work on in the tropics are considered Calcium rich at ~1800 mg/Kg total Ca. that is .18% Ca or the same as adding 9 grams of CaCO3.
I added 2 times that amount.

This also doesn't count Calcium already in the bentonite which already has significant levels in it.
http://en.wikipedia.org/wiki/Bentonite

The tank should hold the weight. A 20 gallon high (24L X 12 W X 16 H) will weight 180 lbs just from the water. Not counting gravel that is added too.

Your shelves may be another issue!

My recipe is ~28% bentonite (I just realized i left it off the list!)
this stuff is real cheap (25 lb for $3). the EPK is ~50 cents a lb
the oxides are expensive but you do not need much of them.

As for finding good local soil try to find an area that is not in active agriculture. Even better is to find an organic farm

Matt

**REVISED SOIL RECIPE** (forgot an ingredient)

Not sure how it happened but I left off an ingredient to my "from scratch" soil recipe. If you look the percentages I gave in my initial post do not add up to 100%! Below is the recipe including bentonite:

This soil recipe makes soils from "scratch," all ingredients you can get from a grocery store and local pottery supply.

here is the general recipe in grams of ingredients and percentages:
kaolinite (EPK) 1100 56%
Bentonite (kitty litter) 550 28%
Fe Oxide red 70 4%
Fe Oxide Yellow 70 4%
Al oxide 60 3%
sugar 15 1%
cornstarch 15 1%
gelatin 10 1%
soy protein 10 1%
CaCO3 20 1%

The sugar also helps with aggregate formation acting like glue between clay particles. Much as sugar on the floor will make you stick to it.
The corn starch acts in a similar way tot eh proteins both are long organic molecules that can interact with different clay particles and each other to form clumps (like pudding or Jello).

The corn starch gets activated by boiling water causing it to denature and unravel. Cornstarch is often used as a thickening agent in food but first must be boiled otherwise it does not in that application.

Tropical soil is ~%5 organic matter or less. which is the amount the recipe calls for. However soil is not composed of labile forms of organic matter (like I have listed above). The organic matter in your soil will be rapidly consumed by fungi, bacteria and other soil fauna. The bacteria and fungi will eventually die and their decomposing bodies will form NEW soil organic matter that is less labile and much more diverse. Do not be surprised or worried about mold in the soil. It will pass. you can also decrease the amount of organic matter by half to reduce this further (which I plan to do in future batches).

The oxides role is not entirely understood but they are associated with pseudosanding/microaggregation the oxides seem to interact with other soil cations (Ca, Mg, etc) and soil organic matter to help promote structure. The paradox of tropical soils is that the oxides in them should be leaching out from all the rain... but they don't so something is helping them stay in the soil.

hope this helps

Matt

Error in recipe!

Guys I found an error in my recipe, I thought I had fixed it. below is the proper percentages:

here is the general recipe in grams of ingredients and percentages:

kaolinite (EPK) 1100 56%
Bentonite (absorbent clay kitty litter) 550 28%
Fe Oxide red 70 4%
Fe Oxide Yellow 70 4%
Al oxide 60 3%
sugar 15 1%
cornstarch 15 1%
gelatin 10 1%
soy protein 10 1%
CaCO3 20 1%

iljjlm said:

Here is a link to a page on rainforest soils.
http://rainforests.mongabay.com/0502.htm
The article starts out by talking about how and why the soils are poor in nutrients.

Click to expand...

The article has some good information but wikipedia has an equally good cited article.

http://en.wikipedia.org/wiki/Rainforest
"Despite the growth of vegetation in a rainforest, the actual quality of the soil is often quite poor. Rapid bacterial decay prevents the accumulation of humus."

iljjlm said:

"Since the first six to eight inches (15-20 cm) of soil is a compost of decaying leaves, wood, and other organic matter, it is the richest source of nutrients on the ground."
"Many tropical species have roots that actually grow out of the ground to form a mat on the forest floor in order to more efficiently collect nutrients. These tiny roots form a network that, along with the mycorrhizae fungi, rapidly absorb nutrients."

Click to expand...

This is true but makes it sound as if the plants grow roots into the decaying plant material. This is not the case in most of the tropical rainforests. It may happen in the case of decaying trees, but for most of the floor space int he forest it is covered by just fallen leaves (and flowers and fruit depending on season). It is however very typical in other forests, particularly temperate and boreal forests (without earth worms).

iljjlm said:

So a question I have is: If we use these clay based soils should we also have a small layer of organic matter on top for nutrients/isopods/springtails etc?

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Actually if you read back to the inception of this concept, or even perhaps just this thread, the original idea was the leaves being present. The mineral soil was added as a way for the arthropods decomposing the plant material to get a better calcium balance (among other things). Together it is meant to better mimic a natural system. The importance comes int he soil and the leaves. The interface of the soil and the decaying leaves is an important junction. In some systems it is a fairly discrete line, other times the macroinvertebrates actually mix the two layers making it hard to say where one begins and the other ends.

Glomalin

Just wanted to post an update with some ideas for the soil mix, though I have not tried them yet. They incorporate ideas that Brent and Ed have already mentioned.
My recipe calls for 5% organic matter, labile organic matter. Organic material that bacteria and fungi readily consume in soil. The result is that the soil mix gets moldy! This is not a bad thing however. Certain arbuscular micorhizae fungi produce an organic material that is excellent for holding soil together. It is estimated to be ~1/3 of all soil organic matter. It is protein and sugar based but surprisingly resistant to decay (though it is documented to decay faster in warm environments).

Using the soil recipe and inoculating it with fungi spores could help glomalin formation and aid in structure of the soil so it does not turn to sticky clay.

It is also stabilized/tighly associated with iron cations, another ingredient in the soil mix.

In January I will try some experiments with this

stchupa said:

Why no volcanic rock? I assume this includes such things as pumice?

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do you mean volcanic rock as in Lava rock (lots of air spaces and pores) or do you mean soil of [recent] volcanic origin?

bbrock said:

My mix came from just trying to replicate the look and feel of a single sample of Panamanian soil that Matt was kind enough to share. I'm sure there are other ways to create an "authentic" tropical substrate.

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On a side note that Panamanian soil is a bit different than how it was originally classified in the literature. It is an Ultisol not an Oxisol (yet to be keyed out... but maybe I will give it a try). The main difference between the two is the oxide content, base saturation (amount of mineral cations), and some minerology. (all of which relate to age which relates to weathering). So the Panama soil may have more in common with the red soils of the southeast united states than the amazon.

Here is a link to a soil map of the:

World:
http://www.wv.nrcs.usda.gov/news/images ... osterw.jpg
United States:
http://www.nrcs.usda.gov/technical/land/lgif/m4025l.gif
South America:
http://culter.colorado.edu/~kittel/soil ... rd_umn.jpg

stchupa said:

That's what I'm asking you, which type of volcanic rock not to use and why not use it?

Click to expand...

The general theme of this thread lately has been the importance of soil, leaves and microarthropods and how that relates to better nutrient balance of the food for the frogs (diversity of organic compounds and a better mineral content).

Lava rock is very porous. If the bubbles are not isolated within the rocks crystal structure the arthropods can live in it and have a safe habitat away from predation by frogs. The lava rock/pumice will do little to add to the mineral content of the arthropods until the rock itself starts to break down which could take decades to centuries depending on conditions.
As Brent mentioned in his post volcanic rock has a high glass content and there could be sharp edges that could hurt the frogs (however neither of us has specific data to say if that will or will not happen).