Why take the risk?

Soil matters
with Peter Burton
Functional Fertiliser Ltd

Hands up if you’ve recently read the health warnings on a bag of magnesium oxide. It’s widely used for dusting of pastures to help prevent calcium/magnesium-related metabolic disorders.

From now until October the sight of quad bikes with small spreaders whizzing around paddocks in front of white clouds is common.

I know that either the warning on the bags hasn’t been read or has been ignored because most of the drivers are not wearing a face mask and protective clothing.

And there’s other reasons for thinking carefully before purchasing magnesium oxide, and one of those is where it comes from.

Can we be certain that the analysis is accurate, and there’s not traces of other stuff in the product that could over time be harmful?

That question is relevant when there’s a New Zealand product that is so safe you can eat it.  It’s sold as a health supplement and it would be near impossible to overdose on it.

It’s Golden Bay dolomite and it is way more effective at preventing calcium and magnesium related metabolic disorders in lactating animals prior to and after calving. 

It’s only necessary to apply it once, typically in autumn, and the recommended application rate is 200kg/ha for intensive dairy. However, it may be applied at any time of the year.

Applying at a heavier rate will not improve animal health, although there may be soil health benefits, and that’s a different discussion.

One of the common objections is that dolomite is less soluble than MgO with the inference that it takes longer to work. That’s not our experience in 30 years of providing it for farmer clients. 

Where there’s been an SOS due to cows going down and not responding rapidly to treatment, an application of dolomite at 200kg has alleviated most of the issues within a fortnight. 

For even more immediate effect it can be placed in a bin, by itself, somewhere animals have access to and are able help themselves, and they will if they are short of magnesium.

There’s a misconception that because it also contains calcium it can’t be used close to calving. Dolomite applied to pasture at 200kg/ha can do no harm to animals unless they are already receiving excess magnesium directly, which is easily remedied.

Dolomite, technically a marble, and therefore extremely hard, is finely ground to ensure excellent bio-availability, with the added advantage that what is not ingested by animals remains in the soil.

Long-term soil testing of farms receiving 23kg/ha of magnesium (200kg of dolomite), shows a steady rise in plant-available magnesium over time.

I’ve yet to see a long-term increase in soil magnesium levels as a result of application of highly soluble magnesium oxide.

We don’t fully understand how it works as effectively as it does, nor have I found any explanation that does. However, that doesn’t alter the fact it is the most effective solution to metabolic disorders at calving.

Experience over many years indicates the annual maintenance magnesium input for intensive dairy properties is around 20kg/ha, with properties receiving 23kg/ha having a steady increase in soil test numbers.

Dolomite has a range of other benefits due to it being originally a seabed deposit. The Golden Bay deposit, the only one in the country, has been compacted due to land movement over time and is mined in the most environmentally-friendly manner incorporating the planting of thousands of native trees and shrubs.

Due to the weathering effect primarily of rain, soil steadily loses mineral content and that impacts on the food produced, lowering our own immunity and increasing the likelihood of contracting exotic diseases.

A single application of dolomite each year replaces many of the lost minerals, strengthening our own health and resilience, from the ground up.

For more information, call Peter on 0800 436 566.


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