Wrapping up this series on nutrients, we find ourselves dealing with the important nutrients that are needed in the smallest amount -micronutrients.
Also called trace nutrients in some literature, the essential micronutrient list consists of iron, chlorine, zinc, manganese, boron, copper, and molybdenum.
I was taught by a turfgrass professional that iron would give you the greenest turfgrass, without the extra growth that nitrogen gives you. Chlorine often surprises folks. I’ve never seen it as part of any fertilizer, as much of it is found naturally. Zinc is heavily used by pecan trees. To help pecan trees grow fully developed leaves, growers add zinc as a foliar spray. Most homeowners will try and put a fertilizer with zinc on the ground around their trees. Though some will be taken up, the foliar application is highly preferred.
Manganese should not be confused with magnesium. Manganese is necessary for photosynthesis. Boron is sometimes found missing for proper clover production. I once erroneously remarked that perhaps we should just add one pound of boron to each acre of clover we plant. Needed in such incredibly small quantities, adding that amount could prove disastrous. In fact, the only time I’ve seen ground-water kill gardens and lawns was when an old shallow well had too much boron in the water.
I have no interesting anecdotes for copper and molybdenum. I do often use molybdenum as an example in a sentence just to demonstrate how we don’t know all the inputs a plant may need.
All of these micronutrients are probably in your soil. You will certainly get them from the addition of organic matter, such as compost. I believe that one of the many reasons organic matter is awesome is because of the natural inclusion of these trace nutrients. You can also find molybdenum and the others on products such as Peters Plant Food and Miracle Grow. I think those products are “miraculous” because they do contain the entire roster of plant nutrition in their bottle.
New to my knowledge of plant nutrition are four more nutrients that research states are needed by just a few plants. These ‘new to me’ ones include nickel, cobalt, silicon, and vanadium. Nickel activates several enzymes and may even substitute for zinc and iron in some processes. Cobalt has been found through research to be beneficial to some plants though not essential in most species. Silicon makes this list, not as an essential nutrient, but as one that has been found in healthy plants as it aids with their structure.
Vanadium may be required by some plants, but a publication from 1999 by the United States Department of Agriculture also says it may just be “junk food” for plants. More recent research states it can be toxic to at high levels. Perhaps more studies need to be conducted, but I would not worry about vanadium in your garden.
The study of plant nutrients is heavy on chemistry, biology, and the research is ongoing. You listen to what your grandparents told you what they used to put in their garden or imitate what your neighbor does for their successful lawn. But if you really want to get it right, spend the $20 and send in a soil test. If you are waiting for any recommendation on how much fertilizer to put out from this series, you won’t hear any from me. To get it right, really correct, you’ll need to submit soil sample. Texas A&M and many other land-grant universities have a form online that you can download and print, or you can easily get the form from your local Extension office.
