The Magic of Molybdenum

Which often-neglected trace mineral can seriously reduce your fertiliser costs, decrease insect pressure and increase shelf-life of your produce (even though it is applied at just handfuls per hectare)? This same micronutrient, often ignored in soil tests, has also been shown to increase yield by as much as 600%!

Accessing the Free Gift – The Magic of Molybdenum

There are several soils on the planet that have remained immensely productive for thousands of years, without a single application of nitrogen (N). The Great Plains in the US was a prime example (we are not sure they are still an example). How did these soils manage to consistently produce more biomass per hectare than the most intensively fertilised soils, without a whiff of urea? Nitrogen fixation is the answer. Soil bacteria, when provided with the right conditions, can convert atmospheric nitrogen into plant-available ammonium nitrogen. The planet’s most bountiful soils had optimum access to the 5000 truckloads of free nitrogen gas that hovers above every hectare. There is a recipe required to tap into this “free gift” and the ingredients were all present in these very productive soils.

We have been conditioned to think that the majority of N used to produce a crop comes from a bag, but this is simply not the case. It comes from soil biology, through the recycling of protein from the residues of the previous crop and from nitrogen-fixing bacteria. We are all farming biology to some degree, but those who are aware of this fact can be much better equipped for the role. How does the biological farmer ensure that he gets the maximum delivery of free nitrogen from the atmosphere?

Well, there are five ingredients in the recipe including; a good calcium to magnesium ratio (to deliver oxygen to the nitrogen fixers), a supply of soluble phosphate (to fire the enzymatic reaction required), cobalt (a trace element which is like mother’s milk to nitrogen-fixers) and the two micronutrients needed to make the nitrogenase enzyme that facilitates nitrogen fixation. These two minerals are iron and molybdenum. Iron is the most abundant mineral in the universe, so it is not usually a limiting factor. However, molybdenum is missing in most of the many soils that we test from around the globe. In our Soil Therapy™ tests we like to see a minimum of 0.5 ppm of molybdenum and this is rarely achieved.

Molybdenum for the Microbe Workforce

Soil testing in Australia has traditionally measured NPK and sometimes included calcium, magnesium and sulfur. It was as if the micronutrients never existed! Gradually, this simplistic approach has given way to an understanding of the importance of trace minerals in plant nutrition, and now most tests include at least five micronutrients. However, there still remains a lack of understanding about the importance of micronutrients to the microbe workforce. It is not just that the microbes require the same minerals as animals and plants; there is also a powerful nitrogen link.

The hyphae of beneficial fungi can grow 40 micrometers in an hour in comparison to the limited mobility of a single-celled bacterium (just 6 micrometers in a lifetime). Protein is constantly required for the ongoing expansion of hyphae and nitrogen is required to build protein. This nitrogen is largely supplied by nitrogen-fixing bacteria in one of the most profoundly important synergistic relationships in the soil foodweb. If, for example, you can get a partnership firing between mycorrhizal fungi and a free-living, nitrogen-fixing bacteria called Azotobacter, then you have hit paydirt!

This “perfect pair” will work together to deliver nitrogen, phosphorus, calcium and zinc and the enhanced supply of these important minerals will help create a thriving plant that will then feed the army of organisms responsible for the delivery of other minerals (potassium solubilisers, iron reducing organisms, manganese reducing organisms, etc). These soil microbes are the bridge between the soil and the plant and biological farming is all about strengthening this cross over point. In contrast, a great deal of what we have done in conventional agriculture has involved bombing this all-important bridge.

The Perfect Partners

Azotobacter require soluble phosphorus to make ATP (Adenosine Tri Phosphate), the power source behind every enzymatic reaction. ATP is constantly needed to fuel the nitrogenase enzyme, responsible for converting atmospheric nitrogen gas into nitrogen fertiliser. The chief role of mycorrhizal fungi is to solubilise phosphate and they also deliver zinc to the plant and to the microbes surrounding the roots. Zinc happens to be the most important trace mineral for Azotobacter.

There is always a two-way street in Nature and the mass of fragile mycorrhizal hyphae attached to the root prefer to source their nitrogen from Azotobacter in favour of stressing their host plant. However, if one little trace mineral is not present in your soil, this “perfect partnership” will fail as surely as your third marriage (40% of first marriages fail, 60% of second marriages and the “third time lucky” is anything but, as there is a 75% failure rate)! This trace mineral is molybdenum and most soils are lacking this critical key. If you don’t have enough molybdenum present you will always need more nitrogen from a bag and these petro chemical-based fertilisers are destined to rise and rise with the onset of Peak Oil.

If molybdenum is missing, you may also have inadvertently increased your shackle factor. You will be more strongly chained to the spray rig because you will have a greater dependence upon insecticides, fungicides and nematicides. It is all about nitrogen again, but this time we are talking about the form of nitrogen found in the plant. That form will largely involve nitrate nitrogen in low molybdenum soils.

Nitrate Negatives

It is now understood that the healthy, disease-resistant plant requires 75% ammonium nitrogen and 25% nitrate nitrogen. Unfortunately, this ratio is inverted in many instances and this oversupply of nitrates, which has virtually become a defining feature of extractive farming, delivers a host of negatives.

If we fertilise with large amounts of soluble nitrogen at planting we are destined to fill the plant with nitrates during the second half of the crop cycle. Nitrification is the biological process where ammonium nitrogen is converted to nitrates. No tiny plant requires the amount of nitrogen that is often supplied as a “kicker” so the inevitable surplus usually enters the plant at a later stage in the nitrate form. Nitrates are always uptaken with water so there is a nutrient dilution factor when nitrates are oversupplied. The nitrate packed, nutrient deficient plant becomes a calling card for insect and disease attack because this is an indisputable law of nature.

Insects are the garbage collectors on the planet. They are keyed to detect (via feelers which serve as antennae) infra-red radiation from plants. A healthy, minerally balanced plant emits a steady flow of radiation while a high nitrate, nutrient deficient plant emits a staccato flow of infra-red rays that calls in the insect. We grow garbage and the garbage collectors arrive!

Some of the key nitrogen management strategies in biological agriculture involve stabilisation of nitrogen inputs (to slow the conversion to nitrates), the use of “ideal” application rates of applied nitrogen to avoid unwanted conversion and the optimisation of supplementary N supply from soil biology. However, there is a critically important additional step required and once again it requires the presence of molybdenum.

Molybdenum to Detox Nitrates

The plant processes involving the conversion of ammonium nitrogen into protein, take place in the roots. This always involves energy, so the roots message the above-ground plant to increase photosynthesis and thereby boost glucose delivery down below. This is one of the reasons for the greening effect associated with application of ammonium fertilisers. Nitrates do not store in the roots awaiting conversion. They move into the leaf where there is a yield-sapping procedure required to convert them to amines, amino acids and finally, protein. This energy draining process, involving 10% of the plant’s net glucose production, requires an enzyme called the nitrate reductase enzyme. This enzyme is dependant upon sulfur and, most importantly, molybdenum. If you have ignored molybdenum, the nitrates remain unconverted in the leaf, the insects receive a calling card and consumers get to eat food filled with toxic nitrates.

Nitrates are a principle root cause of cancer. They reduce the capacity of the blood to carry oxygen to the cells. Dr Otto Warburg won a Nobel prize for identifying the link between anaerobism and cancer and there have subsequently been over 200 published papers confirming the nitrate link to cancer.

The Massive Potential of Molybdenum

Now you can understand how a single, often neglected trace mineral can affect your access to 74,000 tonnes of free nitrogen gas in the atmosphere above each hectare, while also ensuring that your crop has the tools to convert destructive nitrates into protein. It is this type of in-depth understanding that positions the biological farmer to successfully reduce dependence upon petrochemicals in the face of the coming changes.

If a trace mineral is the only thing missing in the mineral equation then it can sometimes prove remarkably productive to address that shortage. One amazing piece of research quantifying this potential was conducted by W.R Lobb in the Waitaki region of NZ. Lobb looked at legumes and canola on both sandstone and clay soils in the Waitaki region of the South Island. Both clay and sandstone soils produced green matter yield increases of between 45% and 300% while one canola on sandstone block produced spectacular green matter increases involving an increase from 7616 lbs per acre to 53,536 lbs per acre – a whopping increase of 603%! It is important to note that subsequent research has shown that the crop must be both molybdenum and nitrogen deficient to respond this dramatically to a mineral correction.

Application Guidelines

There is a suggested maximum application rate of just 2 kg of sodium molybdate per hectare and even at this rate you must be careful to avoid inducing a copper deficit in crops and livestock. If copper levels are marginal in the soil then molybdenum can serve to antagonise copper uptake and reach the tipping point where copper now becomes an issue. In some, low copper, broadacre situations it may be preferable to soak the seed with a 0.1% sodium molybdate solution.

We have found that the NTS products Triple Ten™ and Shuttle Seven™, both of which contain good levels of molybdenum, can serve to fire up the nitrogen-fixers at rates of just 2 litres per hectare. If you are lacking free living nitrogen fixers in your soil then consider increasing your harvest rate of free nitrogen from the atmosphere with a combination of Nutri-Life Bio-N™ (an Azotobacter inoculum) and Triple Ten™.

You can use the NTS Soil Therapy™ service to check your levels and make your own decision about how to correct a deficiency if it is identified. If your soil and crop is lacking both nitrogen and molybdenum, you may be pleasantly surprised at the response to correction.

For more information about NTS Soil Therapy™, Triple Ten™ or Shuttle Seven™, contact us on +61 7 5472 9900 or sales@nutri-tech.com.au.