The forgotten plant and animal mineral micronutrients

Ten nutrient minerals essential for plants and animal nutrition

How many times have you read about plants needing 16 nutrients for growth? The usual carbon, oxygen and hydrogen as well as the macrominerals nitrogen, phosphorus, potassium, sulphur, calcium and magnesium (N, P, K, S, Ca and Mg, respectively). This is followed by micronutrients such as boron, copper, chloride, manganese, iron, molybdenum and zinc (B, Cu, Cl, Mn, Fe, Mo and Zn, respectively).

That’s the 16 elements (minerals) that have been endlessly repeated. Now, with more sensitive detection techniques comes the simple realization all of the minerals we need for life come via plant products. That even includes the very obvious sodium and chlorine, namely salt. How do wild animals get salt? By grazing or ingesting food, which in turn comes from the sodium and chlorine present in the soil.

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We often supplement livestock with additional salt (sodium chloride), especially in areas low in soil salt. Salt, like many other minerals, is fine as long as we or our livestock do not ingest too much.

Now for the rest of the forgotten micronutrients. These micronutrients are critical for all animal life but may or may not play a role in plant life.

I will first list these micronutrient minerals followed by a brief paragraph on the roles of each of these forgotten elements, with the exception of the aforementioned sodium and chlorine.

The minerals cobalt, chromium, fluorine, iodine, nickel, selenium, silicon, tin and vanadium (Co, Cr, F, I, Ni, Se, Si, Sn and V, respectively) are generally present in most soils, ostensibly in non-limiting amounts, but there are exceptions and significant deficiencies, or even toxic levels. I have only included elemental minerals; however, recent research shows that chemical compounds such as nitric oxide plays a role in heart metabolism and hydrogen sulphide (sour gas) plays a role in animal digestive processes.

The forgotten micronutrients

Cobalt — Tiny quantities of this metal element are needed as a co-factor in making the iodine-based hormone thyroxin and the vitamin B12. Cobalt is also essential in trace amounts in the root nodules of legumes in order to fix nitrogen. We did not find out until recently that it had a role in plant growth.

Nickel — Another metallic essential element that is common in several vitamins for normal animal growth. Nickel is also a co-factor in the production of enzymes for converting urea to ammonia in plants. It may be present in plant tissue at little more than 0.05 parts per million.

Chromium — For those shiny truck bumpers! Chromium does not seem to have any defined role in plants but it is important in blood sugar regulation in animals and important for weight gain and diabetes in humans.

Fluorine — This micronutrient is naturally present in many types of well water sources and it’s believed to be important in teeth and bone hardening, but again no role in plant growth or metabolism. Fluoride is the thirteenth most abundant element on earth. Too much fluoride from phosphate fertilizers on pasture may cause a disorder in cattle called fluorosis.

Iodine — Iodine is a critical element in animals in the endocrine system and for the proper functioning of the digestive and reproductive systems. Iodine deficiency retards fetal growth and metabolism. Iodine seems to play no definitive role in plants, although it occurs naturally in plants by uptake from soil and from sources such as seaweed or kelp.

Silicon — This micronutrient is the second most abundant element in the soil after oxygen (oxides). Silicon plays a role in disease resistance in plants and is essential in body fibrous tissue and bone in animals. Plant species such as horsetails (Equisetum sp.) secrete silicon on the outsides of the foliage giving them a sandpaper-like quality. Silicon can be deficient in peat soils and even some mineral soils in parts of China.

Selenium — Heavy sulphur applications to agricultural soil can cause a deficiency of selenium in harvested crops. Selenium has no known function in plants but deficiencies of this element in cattle may cause reproductive and white muscle problems. Soils high in natural selenium along with supplemental feeding of selenium can cause poisoning in livestock including horses.

Tin — This element may have a function in protein structure in animals but none in plants.

Vanadium — Ever heard of this mineral element? It is a trace mineral required in all animals for normal growth and development; however, it has no known function in plants. It has a function in blood formation and reproduction.

All 10 of these aforementioned mineral nutrients are found in plant foods in varying quantities. Some have vital plant functions, whereas others, such as iodine, are just passively picked up by plants and passed along the food chain to animals and us humans. Sometimes these minerals are in adequate amounts, sometimes in deficient levels, but almost all are plant dependent in order to get into the food chain.

Therefore, in addition to the old mantra of 16 essential nutrients in plant growth, you can now add another 10 nutrient minerals, all either plant essential or present passively in plants for animal nutrition.

Now we can state that some 26 nutrients, all supplied by plants in the food chain, are responsible for normal, healthy growth in both animals and humans. In effect, a well-balanced diet for farm livestock must contain these 26 mineral nutrients.

Any one of these nutrients in short supply can inhibit normal growth. Vitamin B12, the cobalt-containing vitamin, can be deficient in animals and man. A lack of iodine can be dangerous, that is why common salt contains iodine — fancy salts do not contain this essential mineral. All these elements together constitute a normal, balanced, healthy outcome when none of these are absent or limiting for plants, animals and humans. Would having all of these minerals in our food constitute what is now regarded as a nutrient-dense diet?

About the author

Contributor

Dr. Ieuan Evans is a forensic plant pathologist based in Edmonton, Alta. He can be reached at [email protected]

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