In this final installment of a five-part series, Graeme describes the key roles of a trio of more obscure trace minerals. Molybdenum, selenium and cobalt are discussed in terms of their roles in the soil, in plants and in our bodies. There is also some more of Graeme’s black humour, and a fascinating segment on boron, which includes its use to counter arthritis.
Rob: I think we can get one last segment completed before you head to India for your working, wellness retreat. Today, I would like to return to the soil, and mineral management. We might begin with a couple of obscure trace minerals and their importance. Many people never soil test for molybdenum, but you believe this is a mistake. Why should we monitor this mineral?
Graeme: 80% of the soils we test, across many of the 57 countries in which we work, are lacking molybdenum. We only require 0.5 parts per million, on the soil test we favour, but most soils have less than half of that.
Rob: Why is this mineral so deficient across the globe?
Graeme: In many cases it has been mined from our soils and rarely replaced. It is also a leachable anion, a little like boron. Like boron, it is only stored on the humus colloid, and we have lost 2/3 of our humus with the chemical, extractive model. It is also used in the conversion of nitrates to protein. If nitrates are oversupplied, more molybdenum is required. Some hydroponic formulas do not account for the extra molybdenum needed, when the only nitrogen in this model is in the nitrate form.
Rob: What are the roles of molybdenum?
Graeme: The first major role relates to our access to the “free gift”. That’s what I call the 74,000 tonnes of nitrogen gas hovering above every hectare. We were supposed to have access to those 5000 truck loads of urea (equivalent). In fact, it is essential, if we are seeking to maximise resilience.
Rob: How is our source of nitrogen related to crop resilience, and less need for chemicals?
Graeme: In the soil, we are seeking equal amounts of ammonium nitrogen and nitrate nitrogen, while ensuring that we never exceed 20 ppm of each. It is very difficult to ever achieve the desirable ratio of 1:1 between these two minerals as they are constantly swapping around in the soil. The important thing is that we have enough of this most abundant mineral in the plant, while always avoiding the “moron” approach. That’s when we decide something is good, so we put more on.
Interestingly the desirable ratio between these two forms of nitrogen in the plant is different to the soil. Here, we want three parts ammonium nitrogen, to one part nitrate nitrogen.
Rob: Why do the desirable ratios differ? You would assume that the leaf would parallel the soil, as the plant has equal access to both forms of N in the soil?
Graeme: As with many things in the soil and plant, it often comes back to microbes.The zone immediately surrounding the roots, that is receiving the glucose exudates from the plant, is called the rhizosphere. This is where most of the soil life is based. Like real estate, it is all about location, location, location. Consequently, if we are seeking to monitor soil biology, we take soil samples from near the roots. There is also considerable life on the leaf surface. The plant pumps out carbon exudates from the leaf to sustain another community of diverse organisms. This feeding zone is called the phyllosphere. Amongst the leaf dwellers are free living nitrogen-fixing bacteria, like Azotobacter. This direct fixation of nitrogen into the leaf partially accounts for the higher percentage of ammonium nitrogen within the plant, compared to the soil. There are also armies of nitrifying bacteria in the soil, converting ammonium nitrogen to nitrate N, whenever it is moist and warm.
Rob: I guess that this warmth and moisture factor explains why there is often higher nitrate levels in sub-tropical soils, but where does molybdenum come into this story?
Graeme: Both soil and leaf dwelling nitrogen-fixers create an enzyme called nitrogenase, which converts the nitrogen gas in the atmosphere into ammonium nitrogen in the soil, or on the leaf. A key building block for nitrogenase is molybdenum. If you are one of the 80% of farmers missing this mineral, you cannot access the free gift, you have to invest more into nitrogen from a bag, and you will never achieve this desirable resilience ratio.
Rob: That’s a big price to pay! How much molybdenum is required to supply enough to ensure nitrogen fixation?
Graeme: It can be applied effectively in quite small amounts. Often, a foliar of sodium molybdate at just 100 grams per hectare will do the trick. Seed dressing can also be productive at similar rates.
Rob: So neglect of molybdenum can restrict our access to free nitrogen in the right form. Are there any other key roles for this mineral?
Graeme: Yes, there is one other hugely important role. Nitrate nitrogen is housed in the leaf, awaiting an energy-intensive conversion to protein. It is protein that drives the immunity of plants, animals and humans, so this conversion is important. It is the nitrate reductase enzyme that catalyses this conversion of nitrates to protein. This enzyme requires molybdenum. If you are one of the 8 out of 10 farmers missing this mineral in your soil, you are producing low brix, nitrate-dominant plants that are more attractive to insects and disease.
Nitrates can also be carcinogens when oversupplied in our diet. They restrict the oxygen carrying capacity of our blood. Professor Otto Warburg won his Nobel prize for identifying the root cause of cancer. It is called anaerobism (or the bloods incapacity to carry enough oxygen).
Rob: I would imagine that correction of this shortage could produce obvious benefits?
Graeme: That’s for sure! My close friend, the accomplished international agronomist, Steve Capeness, shared his experience with large scale coffee growers in India. There, the simple addition of molybdenum to the program, for the first time ever, reduced nitrate dominance and greatly reduced the need for toxic rescue chemicals.
Rob: I guess home gardeners are as likely to be deficient as commercial growers. Have the formulators of home garden fertilisers included this mineral in their products?
Graeme: It seems quite rare. We have very good molybdenum levels in several of our home garden products, including Life Force Gold™ and Life Force Total Cover™. They are available on our home garden website. I have to get some plugs in somehow. He he!
Rob: Your Life Force® range must rank as one of the most innovative and effective amongst home garden products. I’ve often wondered why you don’t have it in the big retail stores?
Graeme: I guess it is a failing on my behalf. I am so busy writing, teaching and farming, I have really neglected the marketing of this range. Perhaps it could be an opportunity for one of our readers. There is really nothing equivalent out there.
Rob: Yes there is no doubt about it, you are definitely a miserable failure. Haha! Let’s move on now to talk about other minerals. I note that you are one of the few companies recommending measuring selenium in our soils. Why are you testing for a mineral that is typically considered more important for human and animal health, than plant health?
Graeme: You are correct about the importance of selenium for our health. Our most important organ is not our heart, it is our liver. This ill-treated organ is charged with many functions, including digestion and detoxification. The most important mineral for your liver is selenium. The vast majority of us in Australia are selenium-deficient, because our soils are inherently lacking this mineral. In fact, we have barely found a single soil in this country with sufficient selenium. The most important nutrient for your liver is a group of amino acids called glutathione. Selenium combines with glutathione to produce glutathione peroxidase, our most protective enzyme system.
Rob: Does this mineral have any impact upon plant health? It seems that there are many parallels.
Graeme: It was a big surprise to the scientific community when a Swedish study some years back reported a 31% increase in tuber weight, when potatoes were sprayed three times during the crop cycle with selenium. When asked to explain the surprise finding, the scientists involved suggested it was related to “reduced photo oxidative stress”. They were referring to the plant protecting itself from UV radiation. Like all carbon-based life forms, the plant is susceptible to free radical damage from UV. It has a variety of protective strategies to call upon, but the most energy-effective involves the creation of a protective enzyme system called glutathione peroxidase.
Rob: Isn’t that the same system that is so important for us?
Graeme: Yes, there are so many fascinating parallels between plant and human nutrition. When the plant is able to protect itself so efficiently (with glutathione peroxidase, created with selenium), it does not need to draw down upon more energy-intensive protective mechanisms. It invests the surplus energy elsewhere. One outcome was substantial yield increase in the potatoes. We include 200 ppm of selenium in our all-purpose foliar fertiliser, Triple Ten™, and it has proven a very productive additive.
Rob: Wow! You’re slipping some advertising into this blog. He he!
Graeme: We are the only ones adding selenium, so people need to know.
Rob: I’m just teasing, because you are strangely sensitive about sharing this stuff. Let’s move on to cobalt while we are covering the more obscure trace minerals. Why should we be testing for this mineral and correcting our cobalt shortages?
Graeme: This blog now has a huge readership around the globe and, according to google statistics, it has an unusually high percentage of people who read the full document, each issue. I try to make it all about giving the best information I can deliver, to help farmers become simultaneously more profitable and more sustainable. I also want to enhance the health, happiness and longevity of readers. I personally hate blogs filled with advertising. They feel insincere and manipulative. Hence my sensitivity.
Okay, let’s talk cobalt. Now, we have this amazing cobalt product ....He he! Just joking. Cobalt is lacking in 50% of the soils we test across the world. It is a really important mineral for humans and animals, because it is an essential component of vitamin B12. You can hear the connection, in the world cobalamin. B12 is an under-appreciated nutrient, and many of us are deficient. It is hard to find a vegan with enough of this nutrient, unless they are aware and countering the lack of B12 in plant-based foods by supplementing regularly. Symptoms of deficiency include anemia, exhaustion, breathlessness and nervous system disorders. Cobalt is involved in the creation of red blood cells, without which you can’t transport sufficient oxygen around the body. Hence the breathlessness and exhaustion. Your skin becomes pale (anemic) due to the lack of these blood cells. Again, it is important to remember that the root cause of cancer is anaerobism, or an inability to transport sufficient oxygen around the body.
Rob: What is its role in the plant and soil?
Graeme: It is often called “mothers milk” for nitrogen-fixers, because it is essential for the number and size of nodules on legumes and the capacity of the inhabitants of these nodules (rhizobium) to fix nitrogen. Signs of nitrogen deficiency on crops like soybean, peas and mungbeans can often be related to a cobalt shortage.
Cobalt can also reduce cadmium toxicity in the soil. This is no small issue. One of my American corporate clients told me that the EPA has measured excesses of cadmium in most food-producing soils in California. This State produces over 3/4 of the fruit and vegetables for the US. Cadmium is hugely linked to prostate cancer, but the EPA is apparently hamstrung, because of the implications of shutting down national food supply. The Mexican farmworkers are not about to move to the Midwest. The US should be having a National Mexico day to celebrate the people who produce their food, rather than building a wall!
Rob: It is an injustice to be sure.There are very few “Americans” out there in the fields, just as there are few English folk doing the hard yards on the farm. It is time to give credit where credit is due. What sorts of amounts of cobalt are required in the soil?
Graeme: We like to see a minimum of two ppm in the soil. This mineral is also important for seed germination in dry conditions and it is needed for various processes associated with stem development. You need to be careful when using it as a seed treatment though as, if you overstep the mark, it can reduce the numbers of rhizobium in the nodules. I prefer to see it used in a foliar.
Rob: I think we might conclude this segment by talking about boron, but first I might get you to share another joke. The first one last week seemed to be appreciated, I was thinking that a farmer joke would be good this time around.
Graeme: Weirdly, I only know one farm joke. With my love for bizarre surprise endings, I thought it was a really funny indictment of the cold hard reality of farming, but it bombed in several countries, so I dropped it from my repertoire. Perhaps I will tell you, and you can suggest why I’m the only one who laughs.
Rob : Let’s hear it.
Graeme: Here goes...
A fertiliser salesman drives in the farm entrance and notices the farmer sitting on the verandah with a pig sitting beside him. The animal’s head is nestled in his lap, while the farmer strokes affectionately behind its ears. Thinking it might be a good way to break the ice, the salesman comments, “That’s a pretty good looking pig you have there, but why does it have one leg missing?”. The farmer looks down at yet another city boy salesman interrupting his 15 minute break, and offers an explanation. “This pig is amazing. Two months back, my twin, three-year old grandsons crawled under the dam fence and fell into the water. They were drowning when the pig arrived. He dived in, grabbed each of them by the shirt and dragged them ashore. He was there jumping on their chests to revive them by the time their frantic mother arrived. This pig is something pretty special.”
“Wow that is amazing, but why is one leg missing?” ventured the salesman.
“This pig!” exploded the farmer, “last month a spark from the fire landed on the mat while me and the wife were sleeping. A fire caught hold and we were unconscious upstairs from the smoke. This pig braved the flames and dragged each one of us downstairs and outside. He then raced next door, sounded the alarm and they saved most of the house. This little guy definitely saved our lives and the house,” he said warmly patting the pig on his broad back.
“Yes, but what about that missing leg?” enquired the impatient salesman, now keen to move on to selling his NPK and chemicals.
“This pig” boomed the farmer, “Last week, there was a breakout from a local prison farm. Two inmates had my wife bailed up in the kitchen. They hadn’t seen a woman in many years and it was clear what was on their minds. They had the missus pinned to the table when the pig rushed in. He grabbed the largest one by the balls and I heard the ungodly screams from the paddock. I grabbed the shotgun from the ute and soon had them rounded up. This pig saved my wife.”
At this point the salesman was losing patience. “For goodness sake,” he pleaded. “What about that missing leg?”
The farmer looked down at him like he was some kind of insect that crawled from under a rock and said with an incredulous tone, “You city boys are completely clueless. When you get a pig this good, you never ever eat him all at once!”
Rob: (laughing). I know why the joke failed. You overdid the hero pig element. Once people invest in this cute little guy, they are never going to respond positively to the shock punchline.
Graeme: I guess you’re right, but I can’t figure out how to make the pig less cute. Perhaps he needs some fleas, scabs and bad habits like Coldwater (from the last blog). He he! I think I might have to leave that one on the shelf. There is nothing worse than faces contorted in shock and horror, when you’re hoping for uproarious laughter.
Rob: Okay, so let’s move on to discuss boron. You consider it to be a more important mineral than many realise. Can you tell us why?
Graeme: Boron is deficient in most of the leaf tests we analyse from all over. We like to see luxury levels of this mineral in the plant, as it is one of the four minerals critical to maximum production and minimum problems. We call this group, “The Big Four”, and the other members of this productivity quartet include calcium, magnesium and phosphorus. If you can optimise leaf levels of this group, you will be smiling at the end of the season. Boron is the surprise member in this exclusive group, but when we look more deeply at the key roles of this trace mineral, you come to understand the inclusion.
Boron is calcium’s indispensable sidekick. Many do not realise that you will never see the full benefits of liming, in a boron deficient soil. Gary Zimmer said it well when he claimed that, “Calcium is the trucker of all minerals, and boron is the steering wheel”. That’s exactly how it works. Calcium sponsors the cell division required for a healthy spring flush, for example, but it does so much less effectively, in the absence of boron.
Rob: Doesn’t boron have its own roles besides synergising calcium?
Graeme: Yes, it has several important roles. It is hugely important before flowering and most crops we monitor have insufficient boron in the plant at this time. Boron improves the fruit to flower ratio by lengthening the male pollen tube to improve reproductive efficiency. One of the single most productive strategies any grower can embrace involves a simple foliar spray of boron before flowering.
Rob: How much boron should be applied at this time?
Graeme: Typically we would foliar spray one kilogram of sodium borate (soluble boron) per hectare on orchard, vine and vegetable crops, but it might be 700 grams on a broadacre crop, due to the lower water rate used. Sodium borate should always be combined with humic acid to stabilise, buffer and magnify the boron. A boron humate cannot leach, and it is uptaken 30% more efficiently than the standalone product.
Rob: Aren’t some crops, like avocados, more hungry for boron than others?
Graeme: Avocados seem to have a huge hunger for this mineral. Growers who understand this thirst will often fertigate several kilos of soluble boron before flowering and then foliar spray double rates (2 kg per hectare), as well. Avocados have many flowers, but a very low fruit to flower ratio. We have seen yields double when the male pollen tube is lengthened, in this manner, to enhance pollination.
Rob: I wonder if boron would lengthen the male pollen tube in humans. It would save the pain and discomfort of tying it to a brick.
Graeme: I wondered about the purpose of those bricks outside your room. He he!
Rob: Perhaps you could explain the concrete block outside your room?
Graeme: (laughing) I guess we had best stop the locker room stuff in case it offends someone. Not that that has ever worried me in the past. He he!
Back to boron. It does play an important role in our health. Boron deficiency in humans is strongly linked to osteoarthritis and sore joints in general. This shortage is also linked to osteoporosis and hormonal deficiency, particularly testosterone. There is a form of boron called calcium fructoborate that appears to be most effective, but the common borax used as an ant killer and laundry aid, is actually pretty effective. It can be toxic at high levels, but so can table salt. It appears that those with vested interest have tried to restrict access to this simple cure by lobbying for a ban on borax-based supplements in some countries.
There is a simple borax recipe, that many swear by, to alleviate these conditions. It involves creating a liquid concentrate by dissolving one level teaspoon in one litre of water. The desired supplementation rate, as a corrective, is 7 mg per day*. That dose is achieved by mixing one teaspoon of this DIY liquid concentrate in a glass of water, and taking this dose twice daily with meals. If you are just seeking a healthy maintenance dose, then you just take one teaspoon of concentrate per day. There is evidence to suggest that boron works synergistically with magnesium, so it would be a good strategy to supplement magnesium in conjuncture with boron.
Rob: There are a great deal of people out there with joint, bone and hormonal issues. I guess they could google a source of calcium fructoborate, if they were uncomfortable with the DIY solution. Does boron have other roles in the plant?
Graeme: It can indirectly have quite an impact on soil life. It is all about the nexus between the roots and the surrounding soil microbes. The plant feeds this supportive community with a daily stream of glucose exuded from the roots. In the late afternoon each day, a trapdoor opens in the chloroplast sugar factories and allows the movement of the glucose produced from photosynthesis, out of the chloroplast. This sugar energy source is then used throughout the plant and 30% is gifted to the microbes around the roots. That trapdoor is controlled by boron, and a B shortage can literally shut the door. In this event, the microbes no longer receive their daily sugar hit – when you starve your workforce, problems kick in shortly thereafter. This is something to avoid at all costs, and it represents another use of that important little tool, called the Refractometer. When you compare late afternoon brix levels with early morning brix levels on the same plant, you should always see a lower brix level in the morning. This reflects that transport of glucose out of the chloroplasts, because you are partially monitoring sugar levels with this meter. If the brix is the same, when comparing morning and evening readings, then you have discovered a boron deficiency. You effectively have a constipated plant, where the sugars are trapped above ground, and you should foliar spray boron immediately.
Rob: That sounds like an important thing to avoid. The refractometer is certainly a versatile tool. Isn’t boron also linked to misshapen fruit?
Graeme: Yes, deficiency symptoms include misshapen fruit. They also include split root vegetables and hollow stem broccoli. Boron is an immobile mineral, so the deficiencies occur on the new leaves. It is involved in the creation of cell walls in rapidly expanding new growth at the growing point. When boron is lacking the growing tip often aborts. This pinches the tip and can create a bunch of new branches that are brittle and distorted. The dieback, associated with vine crops, is also part of this abortion of the growing tip, associated with a boron shortage. If you see a hole in the stem of broccoli in the supermarket, do not choose that food for your family. It that crop was boron deficient, it was also struggling for calcium. The weak cell walls made it more attractive to insects, and the inevitable insecticides can not be easily washed from this particular food, due to the massive, enclosed surface area involved.
Rob: You are a big fan of foliar sprayed boron. Isn’t there some controversy about whether plants can uptake foliar boron?
Graeme: Yes, I believe that a simple foliar spray of boron, before flowering, will benefit most crops – and the payback in terms of cost-to-benefit ratio can be really impressive. Most leaf tests we look at are boron deficient, in terms of the luxury levels we are seeking. In one recent study, involving boron deficient sunflowers, a foliar spray of solubor (sodium borate) midway through the vegetative stage, and again just before flowering, was responsible for a 20% yield increase. That’s a big return on a $5 investment.
There was a belief that boron could only be uptaken through the roots, but there have now been multiple studies that have demonstrated otherwise. You won’t fill the head to the top in a boron-deficient cereal crop, and this will always affect yield potential. Some crops can be remarkably responsive. In a trial I was reading in the Journal of Biological Sciences, they applied varying rates of boron, but the highest rate delivered the biggest response. That involved yield increases of 79.5%, compared to the boron-deficient control.
Rob: I grow turmeric. What rates were involved here and did this involve a foliar spray?
Graeme: There were no foliars used here, but we can assume that they would be very productive for both tumeric and ginger, when applied several times in a season. I am certainly planning that, in both crops, on my farm next season. The boron in that study was mixed with 5 tonnes of manure and applied at planting at the rate of 3 kg of actual boron per hectare. That is a very high rate. If we were talking borax, we are talking around 25 kg per hectare, which I consider to be the maximum rate. In terms of Solubor, 3 kg of actual boron would equate to around 14 kg of sodium borate per hectare.
Rob: Well, my friend, that brings to an end our five-part interview series. Thanks for sharing so freely. I am sure that many have benefited from this information.
Graeme: It’s been a pleasure. Thanks for your involvement. I head to India in the morning for a brief tour, before my Ayurvedic cleansing. I’m hoping to lose some of this gut fat. My constant travelling and eating out is not good for weight management. You don’t have to get involved in the complexities of nutrition science to improve your longevity. Just lose the gut. In one study, it was found that the spare tyre, increases by 500% the likelihood of succumbing to the ten degenerative disease that most commonly kill us. That sounds like a pretty good reason to shed the gut fat and I will be trying hard.
Rob: Let’s do this again sometime, as you have so much to share.
Graeme: Sounds good to me.
*Disclaimer: This content is a personal view only and is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.