Minerals, Microbes and Turf Resilience

NTS has been working in sustainable turf management for over 15 years. There are now multiple golf clubs, turf farms and sports fields that successfully utilise biological principles and products. These include iconic venues like the Royal Selangor Golf Club in Malaysia, Sheshan Golf Club in Shanghai, Le Touessrok in Mauritius, the Headlands Golf Course in Queensland and Wembley Stadium in England.

There is a growing recognition that chemical turf management is not the “essential” that many were led to believe. In fact, working with nature rather than against her can be more productive and dramatically more sustainable. The bankruptcy of the chemical approach is best exemplified with global figures that reveal an ever increasing use of chemicals (up 14% last year) while total pest and disease pressure continues to increase each year. You cannot throw on more chemicals with less and less response. It is literally the definition of “unsustainable”.

Five-Part Path to Resilience

The solution to the problem always involves addressing root causes rather than treating symptoms. The root cause of pest pressure is always linked to mineral balance and availability, the presence of beneficial microbes and associated plant immunity. The five strategies that help achieve these goals include a combination of mineral management, biological inoculums, immune elicitors, photosynthesis enhancers and a cell-strengthening strategy.

1) Mineral Management

The key strategy here involves the principle that no mineral is an island. Every mineral affects the uptake of at least one other mineral and the secret is to work toward an optimum balance where the availability of all minerals is maximised. The other mineral management strategy involves a recognition that a broad spectrum of minerals is required to build a resilient plant and many of these are not included in many nutrition programs.

We suggest that turf growers utilise our Soil Therapy™ service, as this soil testing and programming service is based upon a proven mineral balancing philosophy. There are a number of key ratios we seek to achieve in your soil, the most important of which include the following:

a) The ideal calcium to magnesium ratio – this mineral ratio governs the efficiency of gas exchange. This is arguably the most important process in plant growth and soil health as it involves the entry of oxygen into the soil (to feed the roots and the army of protective organisms living around the roots) and the exit of CO2 as the roots and the organisms breathe out. The better the Ca/Mg ratio the better the gas exchange, the healthier the soil life and the happier the turf.

b) Equal ppm of magnesium and potassium – if this can be achieved, you will see optimum uptake of both of these minerals (as evidenced by a leaf test) and luxury uptake of phosphorus. Excess potassium negatively affects the uptake of both magnesium and phosphate, while excess magnesium antagonises potassium uptake. Magnesium is also a phosphate synergist, which enhances phosphate uptake. So if you get the magnesium to potassium ratio at 1:1 in the soil, you will achieve the best possible uptake of all three minerals. It must always be remembered that phosphorus is a key fuel for the plant’s immune system, as it provides the ATP that is required for all enzyme reactions. We rarely see the luxury levels of phosphate in the leaf sought to achieve maximum plant immunity, and this is a good tool to address this issue.

c) A phosphorus to zinc ratio of 10 to 1 – these two minerals have a major impact on each other and maximum uptake of both is possible if you can achieve this 10:1 ratio on a soil test. Remember the importance of phosphate in plant immunity and recognise that zinc is the trace mineral that governs the production of auxins, which in turn govern leaf size. The leaf is the solar panel that determines productivity and plant health.

**Nitrogen Management and Resilience **

Nitrogen is the mineral most abused in turf management. It is invariably oversupplied and often in the wrong form. It is critically important to ensure that your turf is not packed with nitrate nitrogen, if you are seeking to avoid disease pressure. Nitrate nitrogen is always carried into the plant with water and there is an associated dilution factor involved. High nitrate nitrogen always spells low mineralisation because of this dilution effect. A broad spectrum of minerals is involved in the plant’s immune response and the levels are compromised by excess nitrates.

Aside from the dilution effect, excess nitrate nitrogen also reduces the uptake of two key minerals that are important for resilience. One of these is calcium, which is so important for cell wall strength and associated disease resistance. The other mineral impacted by high nitrate nitrogen is potassium. Potassium is the most expensive fertiliser input in horticulture and it makes little sense to inadvertently induce a shortage of this mineral by oversupplying another expensive input (nitrogen). Nitrogen is the most abundant mineral in the plant and critical for maximum production, so it easy to understand why growers regularly succumb to the “moron” approach (if a little nitrogen is good then let’s put more on). The “Goldilocks” approach is most productive here, but getting your nitrogen “just right” involves close monitoring.

The best tool to help maintain ideal levels of nitrate nitrogen is the Horiba Sap Nitrate Meter. This simple and accurate tool can supply immediate, in-field information about nitrogen status within your turf. There is also a new phone App that monitors nitrogen in turf grass that may prove of value. The mantra becomes “how low can I go” to maintain an appealing green. Nitrogen is the most abundant mineral required for plant growth, so it is critically important that it is not undersupplied. Conversely, it is the mineral that is most often oversupplied, so precision in nitrogen nutrition is essential.

Molybdenum and Nitrogen

Molybdenum is a critical trace mineral for nitrogen management, which is frequently overlooked. In our work in over forty countries, we find that molybdenum is deficient in over 80% of the soil tests we analyse. Molybdenum is a crucial component of the nitrogenase enzyme, the tool used by nitrogen-fixing organisms to convert nitrogen gas in the atmosphere into ammonium nitrogen in the soil. You simply do not have access to the 74,000 tonnes of free nitrogen in the atmosphere (which helps ensure the desirable 3:1 ratio of ammonium nitrogen to nitrate nitrogen in the plant) if you have neglected your molybdenum. Similarly, your crop will accumulate nitrates in the leaf and become more susceptible to disease if molybdenum is not present. This neglected mineral also provides the building block for the nitrate reductase enzyme, which serves to convert nitrate nitrogen through to protein.

Broad Spectrum Mineralisation

The first cell that oozed from the pre-Cambrian ocean contained 74 minerals and it is a safe bet to assume they all have a purpose in the perfect blueprint that is Nature. Soluble kelp and liquid fish are the mainstay of the biological approach, partly because they still contain that full range of minerals. The science of plant immunology is still in its infancy, but I believe that we will eventually discover that immune elicitation involves more than the 17 minerals currently considered. Selenium is a good example. This mineral is never tested and yet new research suggests it serves as an antioxidant within the plant to counter the oxidation associated with twelve hours of unbridled sunshine each day. Antioxidants are invariably protective on many levels and this is one of the reasons why we have been one of the first companies to include 200 ppm of selenium in our best-selling foliar, Triple Ten™. The practice of broad-spectrum mineralisation offers more than increased plant health. It also stimulates and nurtures the microorganisms that are an integral component of resilience.

2) Microbe Mastery – Inoculums for Disease Management

The use of biological inoculums amounts to expanding the life force in the soil to reap the benefits of a new, task-specific workforce. There are inoculums of inhibitory bacteria or predatory fungi that have been shown to impact pathogens on several levels and it is these well-researched, multi-purpose microbes that are important in any resilience program. The five organisms with most promise in this context include Mycorrhizal fungi, Trichoderma, Pseudomonas fluorescens, Bacillus subtilis and Azotobacter.

a) Mycorrhizal fungi are missing in 90% of our soils, but in turf situations, that percentage may be even higher. These creatures cannot handle the nematicides that are so widely used in turf management. Mycorrhizal fungi provide a massive root extension that amounts to a ten-fold increase in root surface area. They increase access to immobile minerals, stabilise and magnify mineral uptake and there is comprehensive research linking plant resilience to mycorrhizal colonisation. Part of this increased defense capacity comes from the biological delivery of phosphate (arguably the most important mineral for plant immunity). There is also evidence that mycorrhizal fungi produce biochemicals that elicit an immune response in the plant.

b) Trichoderma is a cellulose digesting, free-living fungi that is often compromised by turf chemicals, including copper. Trichoderma does more than build humus, however. It is also a predatory fungi that feeds upon a wide range of pathogens and it produces antibiotics that further compromise the undesirables. It releases acids that solubilise locked-up phosphate in your soils and, most importantly, in this context Trichoderma activates plant defense mechanisms via the production of protein-based immune elicitors.

c) Pseudomonas fluorescens is a ubiquitous, protective bacteria that is seriously compromised by glyphosate and, as this herbicide is widely used in turf production, there is a question mark about the disease-suppressive capacity of these soils. These organisms produce a variety of anti-microbial compounds, including antibiotics and hydrogen cyanide.

d) Bacillus subtilis forms a stable, extensive biofilm and secretes a biochemical called surfactin. Biofilm and surfactin combine to offer protection against a variety of diseases, including downy and powdery mildew. Surfactin is a powerful lipopeptide, an anti-microbial agent. This versatile organism also produces a substance called acetoin, which has been found to trigger induced systemic resistance (ISR) to produce a more resilient plant.

e) Azotobacter inoculums can provide substantial amounts of ammonium nitrogen via nitrogen fixation, while also offering a suite of other benefits. These organisms are known to suppress phytopathogens or reduce their deleterious effects. Several researchers have confirmed the reduced incidence of fungal, bacterial and viral diseases in crops inoculated with Azotobacter (Sidorgy, 1954; Samitsevich, 1962; Singh, 1977 and Meshram, 1984). The antagonistic mechanisms linked to this protection include the production of siderophores, anti-fungal compounds and defense enzymes.

Task Specific Microbe Blends

A cost-effective strategy that is widely employed in biological golf course management involves multiplying or “brewing” your own organisms. Nutri-Life 4/20™ is multiplied over a 24-hour brewing process using inexpensive brewing equipment and applied at 100 litres per hectare. A food source called Liquid Microbe Food (LMF™) is added during brewing at the rate of 1 litre per 100 litres. It is also possible to select for either bacteria or beneficial fungi with the addition of a second liquid called Dominate-B™ or Dominate-F™, respectively. The addition of Dominate-F™ during the brewing of Nutri-Life 4/20™ at 1 litre per 100 litres, for example, delivers a tank full of beneficial fungal spores, which allows a luxury dose of these organisms at a very low price.

3) Immune Elicitors

This is an area that the industry research bodies are focusing on at present. This is recognition that the plant has a defense system not unlike our human immune system and there are substances that have proven to boost immune responses. We have discussed some of the key organisms involved in immune elicitation, including Trichoderma, Bacillus subtilis, Pseudomonas fluorescens and Azotobacter, but there are other non-biological substances involved that also spark the immune system. One of these is salicylic acid. Aspirin was developed as a synthetic form of salicylic acid to mimic the pain-killing capacity of plants that are naturally rich in this substance (like willow bark and Aloe vera). Salicylic acid is a phenolic phytohormone that is intimately involved in the hormone response. We have found that a 5x concentrate of Aloe vera is a very special liquid fertiliser that can elicit an immune response (Aloe-Tech™). You can even dissolve aspirin at a rate of one tablet per 4 litres of water and apply it as a foliar spray to boost plant immunity, but it will prove more costly than the Aloe vera option, at the rate of 25 aspirins per 100 litres. The other much-researched substance that stimulates immunity is chitin, which is sourced from prawn shells and is now available in commercial preparations.

4) Photosynthesis Enhancement

Photosynthesis is the most important process on the planet, as the green plant is literally the only food source. Anything that significantly boosts photosynthesis increases plant health and resilience. Chlorophyll is the green pigment where tiny sugar factories perform their miracle. Chlorophyll management is the principle role of turf growers. The greater the chlorophyll density, the lower the problems. We use a refractometer to monitor dissolved solids (brix levels) in the crop leaves and this provides a direct guideline as to chlorophyll density. It was with this understanding that I became very excited when I first discovered research into a plant-based substance called triacontanol. This substance is found in the outer waxy coating of the lucerne plant and can be sourced from the wax of bees working lucerne plantings. This is the first fatty acid that has been found to promote plant growth and it does so in the healthiest possible fashion. Most PGP products are based upon some sort of hormonal manipulation and they often deliver increased growth, but reduced nutrient density. Triacontanol, by contrast, boosts chlorophyll density and magnifies production of the phosphate-based enzymes responsible for photosynthesis. In one important study, a researcher named Reis reported a 31% increase in chlorophyll density. The researched benefits of triacontanol in turf include bigger leaves and roots, enhanced photosynthesis with associated brix increases and production of more robust and resilient plants. Nutri-Stim Triacontanol™ from NTS is remarkably cost-effective and applied at just 50 mL per hectare.

5) Resilience Through Cell Strength

The cell wall is the obvious physical barrier that can slow the flow of disease. The two minerals that determine the strength of the cell wall are calcium and silica. Calcium is the mineral we find most difficult to build to the luxury levels required to maximise cell strength. Calcium has terrible mobility in the soil and the plant – in fact it is a slug of a mineral! Foliar sprays of calcium are one way to improve delivery. We find that the simple combination of calcium nitrate with fulvic acid produces a calcium fulvate that is delivered really well.

However, it is the second cell-strengthening component, silica, which is so often the missing link in turf management. Silica is the second most abundant mineral on the planet, but something we have done to our soils has hindered the flow of water soluble silica (mono silicic acid) from the sands and clays of which it is a primary component. We need to see 100 ppm of silicon on our soil test, but most soils present with just 20 – 40 ppm. Silica has become the flavour of the month in agriculture following five International Silica conventions, at which hundreds of new research papers were presented. It turns out that silica is much more than a cell-strengthening mineral. It is actually an immune elicitor of profound importance. Plant immune competence can be monitored by measuring phytoalexins in the leaf, which is comparable to measuring antibodies in humans. Plant-available silica is a major player in generating high phytoalexin counts. Silica also boosts photosynthesis and protects the plant from sodium and heavy metal toxicity. Silica can be applied as potassium silicate, via fertigation, or as a foliar, but it usually involves a standalone application.

Silica is incompatible with almost everything except kelp and humic acid and there have been many a curse from growers who have discovered this the hard way. There is, however, one form of silica that allows more versatility with combinations. In fact, the NTS product Dia-Life Organic™ can be combined with almost anything. Dia-Life Organic™ is based upon liquid, micronised, diatomaceous earth. Diatoms are ancient microscopic creatures that congregated in pools in great numbers. Their exoskeleton consists of 85% silica dioxide and, when the community died out, the abrasive outer shell is all that remained. It was discovered that, if this material was micronised down to 5 microns and held in liquid suspension, it could deliver plant-available silica to the plant. We like to monitor silica levels with leaf analysis and we see substantial rises in silica in the leaf following modest applications of Dia-Life Organic™ to the soil, via fertigation. An initial application of 20 litres per hectare should be followed by 5 litres every ten days. It is important to keep some plant-available silica in soil solution as often as possible. Silica is rapidly incorporated into the cell walls when it is absorbed by plants, so it is important to provide an ongoing supply so there can always be something to draw from.

In Conclusion

Hopefully, it is now clear that there are a variety of proven natural strategies that offer a successful, science-based alternative to chemical turf management. These solutions are much more cost-effective than the chemicals and they do not pose potential health problems for those applying the toxins or those playing sport on treated turf. It is all about addressing root causes rather than treating symptoms and the end result is a healthier outcome for turf, people and the planet.

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