Saturday, February 22, 2014

My Quest for Natural Macro and Micro-nutrients

I invite you to come along with me on my quest for natural sources of both macro and micro-nutrients. Each of the sources quoted are worth reading in their entirety, but I'll present them as I search for the answers.

I have taken to Earthan Beds which are dirt filled wicking beds connected to a bioponic or aquaponic system. Urine (humonia), weed tea, and compost supply much of my bioponic garden's needs.  But one of the most difficult minerals to supply during my experimentation with Soil-Less Bioponics and Aquaponics was iron (Fe2+) in an available form.   For this one mineral I may have to give in to purchasing a product.  The following describes my pursuit,  but first here are some interesting facts you should know 

Common chelated forms (iron-EDDHA, DTPA and EDTA) differ in their ability to hold onto the iron (and therefore keep iron soluble and available to plants) as the media pH increases. Between a media pH of 4.0 to 5.5, any form of iron will work (including iron sulfate) at supplying iron to the plant. However, as the media pH increases above 7.0, only the iron from Iron-EDDHA has high solubility. Research has shown that the ranking of iron forms from most effective to least effective at supplying iron at high media pH is Iron-EDDHA > Iron-DTPA > Iron-EDTA > Iron sulfate. If iron is applied in a form that is not soluble because of high media pH, then most of the nutrient will not be available to plants until media pH is lowered. -

Now that we know what forms of iron are available how do we go about finding a natural source for our garden?  It should be noted that iron, manganese, zinc and copper all require chelation in order to be available to your plants. Generally manganese, zinc and copper chelates are only found in the EDTA form, but Zinc sulfate is generally used because Zinc chelate is too expensive to use at rates needed to increase zinc levels in the soil.

"The worms digestive enzymes (or, properly, those produced by bacteria in the worms intestines) unlock many of the chemical bonds that otherwise tie up loose materials and prevent their being plant available. Thus vermicastings are as much as seven times richer in phosphate than soil that has not been through an earthworm. They have ten times the available potash; five times the nitrogen; three times the available magnesium; and they are one and one half times higher than calcium (thanks the calcium carbonate added during digestion). All these nutrients bind into organic material in the fecal pellets." - .Teaming with Microbes: The Organic Gardener's Guide to the Soil Food Web, Revised Edition (2010) by Jeff Lowenfels &  Wayne Lewis.

Sadly iron is not mentioned as one of the micronutrients made available by worms, but the benefits are obvious an even though Lowenfels and Lewis did not specifically mention iron it may still be one of the benefits.  The balance of evidence suggests that earthworms increase metal mobility and availability but more studies are required to determine the precise mechanism for this -

Iron plays an important role in enzyme functions and is a catalyst for synthesis of chlorophyll. Plants deficient in Fe may exhibit pale leaves and/or yellowing of leaves and veins. Nickel has only recently been recognized as an essential element. It is required for the urease enzyme to break down urea into usable nitrogen and for iron absorption. -

Clearly it's not just iron we need but instead a full spectrum of nutrients, and worms provide many of these.  Also note that most macronutrients are mobile within the plant, most micronutrients are immobile, and so a constant supply is needed for the duration of the crop.  A healthy soil web with worms is crucial to maintaining the constant availability of these nutrients.

If your soil is lacking in certain elements, the best way to add them is through the compost pile. Add colloidal phosphate (organics) or superphosphate for phosphorus and wood ashes for potash. Composted organic materials can also be used as a cheap iron chelate (a slow-release source of iron) to remedy the adversities of iron chlorosis, i.e., yellowing plants. Gardeners can make a "synthetic chelate" in their compost pile by mixing 1 cup of iron sulfate (copperas) for each bushel of moist compost. Particles of iron will adhere to the surface of the compost material and will be released for plant use as the material decomposes while it is being used as a mulch around plants or when incorporated into the soil. -

This gives me some hope of finding a practical method of creating available iron.  Iron sulfate is readily available and inexpensive, but my quest for natural and available sources has not been satisfied. Some plant material high in iron include artichokes, spinach, collard greens, lentils,  mushrooms, and soybeans, so compost these whenever possible.

Below are some relative values I calculated from

I don't throw many nuts away, but they contain a lot of iron. Some common nuts such as pine nuts, hazelnuts, peanuts, almonds, pistachios, and macadamia contain about 0.061%

Beans are also a good source - soybeans, lentils, kidney beans, garbanzo beans, and lima beans, navy, black beans , pinto,, and black-eyed peas contain about 0.037%

Leafy greens - Swiss chard, turnip greens, kale, beet greens contain about 0.036%

Grains & Seeds - pumpkin seeds, squash seeds, oats, barley, rice, bulgur, buckwheat, millet contain about 0.015%

How did our ancestors garden without store bought soil amendments?  Were they just lucky to be the first to plant in the nutrient rich soil before it was depleted?  The natural production and distribution of iron is a process of volcanic action where sulfur and iron are spewed forth along with many other micro nutrients into the jet stream and ocean currents.  The ocean contains most of earths natural minerals which are spread out by strong air and water currents.

Kelp contains enzymes, a lot of potassium, and many other minerals essential for plant growth, making it a perfect garden supplement with about 22% iron. I'll admit I don't know if that 22% is in an available chelated form.  Kelp also contains cytokinin which promotes resistance to bugs, and allows for faster cell division.  You may recall that one of the benefits of insect frass is cytokinin, but I do not wish to diverse.

Kelp Forests
I am not lucky enough to live near an ocean, but kelp is a natural product with many benefits. As much as I would like to curtail my dependence upon commercial products it may be that some products such as iron sulfate or kelp will have to be purchased in order to achieve outstanding results.   Azomite, BT, and  Spinosad are a few others I have come to rely upon, but my quest for independence will continue.

It seems that ferric iron is generally present, so the better solution might be to simply make it available as ferrous iron by adding plenty of organic acids in the form of humus.  Many of the components of humus are heterogenous, relatively large stable organic complexes. They function to give the soil structure, porosity, water holding capacity, cation and anion exchange, and are involved in the chelation of mineral elements. -

 A plant-excreted chelate forms a metal complex (i.e., a coordination compound) with a micronutrient ion in soil solution and approaches a root hair. In turn, the chelated micronutrient near the root hair releases the nutrient to the root hair. The chelate is then free and becomes ready to complex with another micronutrient ion in the adjacent soil solution, restarting the cycle. 
The process works like this:  
A chelate is exuded from a root to the soil solution.  
The chelate complexes a micronutrient (e.g., iron) from the soil solution.  
The chelated micronutrient is carried to a root hair, where it is released.  
The chelate goes back to the soil solution and starts another cycle.

Humic acid, humate and folic acids are mined, and sold, but what if compost can provide the same benefit. It is known that Earthworms (Eisenia foetida) produce several bioactive humic substances which are found in earthworm compost.

The chelating action of humic acid is sometimes used to produce chelated iron products. Without the addition of a nutrient such as iron, the claim is often made that humic acid has the ability to solubilize micronutrients already in the soil. This is a valid claim,but one has to realize that turfgras roots themselves excrete organic compounds that solubilize micronutrients. -

I may be reading too much into this but I think I've found the answer to my my quest for natural sources of chelated iron - Earthworms (Eisenia foetida).
Along with the bioactive humic substances which produce chelated iron;  earthworm's and their compost also provide enzymes, that promote hormonal activity, and make chemical reactions millions of times faster.  Microbes make organic plant food from minerals and dead stuff with the enzymes they produce.

Mart Hale sent these to me.   

Liquid Grass Clipping Fertilizer

Weed Tea / Fertilizer
Gather some herbs from the list below and put in a large container such as a bucket or barrel. Fill with water. Infuse for at least two weeks. This is best to prepare with the new moon and strain and fertilize around the full moon, although it can be done whenever it is convenient.
              Alfalfa, Clover, Soybeans, Field Beans, Vetch, Comfrey, Kelp, Licorice Root leaves, Nettles

        Bladderwrack, Carrot leaves, Coltsfoot, Comfrey, Dandelion, Dulse, Horsetails, Kelp, Meadowsweet, Mistletoe, Mullein, Parsley, Peppermint, Primrose, Willow bark, Skunk Cabbage, Watercress

          Braken fern, Borage, Carrot leaves, Chamomile, Chickweed, Chicory, Clover, Yellow Dock, Eyebright, Fennel, Lamb's Quarters, Nettle, Mullein, Oak bark, Parsley, Peppermint, Pigweed, Plantains, Comfrey, Toadflax, Watercress, Yarrow, Orange and Banana skins

    Barley, Buckwheat, Calamus, Caraway, German Chamomile, Chickweed, Clovers, Dandelion, Yellow Dock, Garlic, Lamb's Quarters, Lemon Balm, Licorice root leaves, Lupine, Marigold flowers, Meadowsweet, Mustard, Pigweed, Purslane, Savoy, Sorrel, Vetches, Watercress, Yarrow, Comfrey

    Gopher Spurge, Cardboard boxes, Beetroot leaves

Coltsfoot, Dandelion, Nettles, Plantains, Valerian, Yarrow, Parsley

Chickweed, Lamb's Quarters, Watercress

               Coltsfoot, Eyebright, Fennel, Garlic, Meadowsweet, Mullein, Mustard, Nettle, Plantain, Shepherds Purse, Watercress, Cabbage leaves, Onions

Sarsaparilla, Bladderwrack, Dulse, Iceland Moss, Kelp
Silicon, Oat Straw, Plantains, Valerian, Borage, Comfrey, Dandelion, Horsetail
Chicory, Comfrey, Dandelion, Nettle, Perilla, Watercress

Willow Tea:
Used for rooting transplants or cuttings. Infuse leaves from a willow tree in water as if you were making an herbal tea for yourself. Once cooled, water the plants that you wish to root with this mixture.

Here is another article that I found quite interesting.


  1. Just a short comment, Eisenia foetida are generally known as compost worms or manure worms. All worms probably produce the same action in that they consume detritus and leave behind rich castings, but compost worms (easily found in manure piles that have been sitting, or from any vermicomposter) may be easier to find in quantity - or their castings. Agree though that this is probably a big part of why worm castings are so prized - full of humic complexes and bacteria that make good stuff bio-available.

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  3. Do you make any test to prove that worm casting contain iron chelated and does it stable in aquaponics condition?

    1. I have not personally conducted tests to see if worm casting contain iron chelate. This information came from more than one source and finally when I understood that it is the humic acids and bacteria that make iron and other minerals bio-available it was clear to me that this is how nature provides the various ionic forms to the plants. Worms digest their food much the same way as we do with bacteria in their gut which in turn transform the mineral's ionic state..

    2. Aquaponics provides a great deal more oxygen to the root zone than soil. Oxygen has a negating affect on some chelates. I can't say with certainty that if the pH is kept below 7pH that the iron will remain available long enough for the roots to up take, but I assume that it would.

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