Nitrogen, Nitrates and Nitrites

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Lions and Tigers and Bears, Oh My! —-

After a lot of years trying different substrates for herps, I found a good quality potting mix to be simply the best. And I recommend Miracle-gro potting mix because it has proven to provide the most consistently high quality product. (See: The Great Substrate Debate, and Comparing Bioactive Substrates)

There are a few folks who have raised concerns over the “chemicals” in Miracle-gro Potting Mix (MGPM), largely because they dont quite understand the science around this issue. The typical concerns reflect an irrational fear based on an incomplete understanding.

The chemical most often singled out as dangerous is “nitrogen”, present in MGPM as ammonium nitrate, a chemical compound with the chemical formula NH₄NO₃. This nitrate is used in massive quantities as a fertilizer (nutrient) for vegetables, lawns and general crop production. It is generally considered harmless unless large quantities are breathed in or consumed.

Miracle-gro potting mix contains 0.2% nitrogen, 0.07% phosphorous and 0.2% potassium. This is obviously a minuscule amount, but even this small bit quickly dissipates. Nitrogen is not only taken up by plants but is broken down by bacteria into atmospheric nitrogen which joins the air. Nitrogen also moves freely thru the substrate so rinsed out of the substrate when watered. Typically the available nitrogen in MGPM is gone within a couple months of opening the bag and emptying it into our vivariums.

But while it is present, is it harming our animals? The short answer is no, not at all. Some of the concern may come from the fact that nitrates can be harmful to gill breathing organisms. When nitrate levels get too high oxygen absorption via gills can be inhibited. This is Aquarium 101 – something we all learned when setting up our first fish tanks. But concern over nitrates in fish tanks doesn’t translate to adult animals that do not breath thru gills.

Infants are also sensitive to high nitrate levels because they haven’t developed the gut bacteria needed to convert nitrate to harmless (actually beneficial) forms such as nitric oxide. Once we are past a few months old, nitrates are harmless to us. In fact food processors add nitrates to meats like ham and bacon, and a number of vegetables have nitrate levels of 500 – 1000ppm in them naturally!

So obviously the fear that nitrate is going to harm our animals is completely unfounded. We eat nitrate as part of a healthy diet. Nitrates are beneficial to our health (although the nitrosamines processors put in preserved meats is suspect in my opinion).

None-the-less, some will respond to all this evidence by saying “I dont want to poison my animals even a little bit!” This is probably where their unfamiliarity with basic science is probably most apparent. It would be like saying “I wont put salt on my fries because I dont want to poison myself even a little bit”. There are many things that can kill us in too great a quantity – salt, vitamins, even water. There is very long list indeed. But a little salt, or a little water, isnt “a little poisonous”. Obviously our bodies easily deal with these smaller amounts, and in fact, just like nitrogen, can not function without them.

So even though the evidence is clear, I want to add some personal experiences. I have kept dozens of species of herps on MGPM. Species like snakes, lizards and turtles, but also frogs like horned frogs that burrow down into the substrate for much of their lives. And I’ve kept dart frogs on MGPM that is only partially covered by forest litter. The frogs were in contact with the potting mix frequently. Finally, Ive used MGPM as a substrate in an aquarium I created for tadpoles of red-eyed tree frogs and Dendrobates. The tadpoles thrived in this tank and metamorphic into healthy froglets.

I have even raised isopods an springtails on MGPM for multiple generations.

So lets find things to worry about that are actually threats and stop beating this dead horse!

1.) https://extension.missouri.edu/publications/wq252

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