How Superior Is Natural Chelation?

CucumberWe are often asked why it is necessary to invest in chelated products rather than simple sulphate-based trace elements so we finally decide to invest some research funds in a comparison. We decided to use manganese as an example as this is a deficiency we see so often when analysing dairy pasture. It is also a common deficiency in many horticultural crops, particularly strawberries, where several of the more recent hybrids seem to struggle with manganese uptake.

To achieve identical rates of manganese we applied 2 kg per hectare of manganese EDTA and 3 litres per hectare of both Manganese Shuttle™ and Manganese Fulvate. The control was obviously not foliar treated with manganese. The EDTA application cost AU$49.80 per hectare, the Manganese Shuttle™ cost AU$32.80 per hectare and the Manganese Fulvate cost just AU$17.35 per hectare. The crop involved in this trial was apple cucumbers. The graph above summarises the findings.

It is important to note that the Manganese Sulphate treatment was not successful as it appeared to induce a deficiency of nitrogen and potassium which actually killed the plants. The naturally chelated products delivered much more vigorous and healthy plants. In fact both the EDTA treated plants and the control developed problems with powdery mildew which were not present on either of the naturally chelated treatments. It makes me wonder if we should not conduct further research looking at a potential protective role for manganese in mildew management.

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  • http://www.geckofert.co.za Hans Ellis

    I have a critical situation where I have a constant defiency of manganese on Citrus on light sany soils.
    We found that foilar sprays were insufficient.Then when mixed manganese sulphate with poultry manure
    and put 50kg per hectar under the trees which 75g per tree. This too does not give the effect what we were expected
    Do you have any idea what to do.?

  • Graeme Sait

    Hi Hans,

    First of all, do you use any glyphosate or has there been a history of regular use of glyphosate on your property in the past? It is not uncommon in orchards, where this is the case, to find severe manganese and/or iron deficiencies in the trees. This is because glyphosate reacts with these cationic micro-nutrients to form glyphosate-metal complexes which binds up the metals and renders them unavailable for plant uptake. Even if glyphosate has not been applied to the soil for some time, it has a half-life in soil of anywhere between several weeks to years.

    Furthermore, soil problems such as high pH due to high magnesium, sodium, potassium or calcium, can also severely limit the uptake of manganese, as can high pH water (which may be the case if using alkaline bore water for example). Even very high soil levels of zinc and copper, (which is also very common in citrus orchards), will limit the uptake of manganese. Therefore, I would persist with the manganese foliar applications whilst you are trying to overcome the limitations in the soil. At what rate were you applying the foliar manganese? What sort of chelating agent did you use? Did you use a good spreader and sticker with the application? And what time of the day was the application applied?

    I would try our Manganese Shuttle™ at 5 L/ha or, if you are certified organic, try manganese sulphate at 3-5 kg/ha with Fulvic 1400™ at 2 L/ha and incorporate a good spreader/sticker such as Cloak™ Spray Oil at 1.5 L/ha. This application will probably need to be repeated a couple of times at 3-4 week intervals. A reliable leaf test should always be taken before and after application to determine the effectiveness of the spray. You can include other sulfur based inputs in this application, but avoid incompatibilities such as calcium nitrate, potassium nitrate, MAP or MKP. Also, avoid spraying in the middle of the day as this is when humidity is lowest and plants are less responsive – very early in the morning or late afternoon/evening is the best time to foliar spray.

    Hope this helps,

    Kind regards,

    Julie