In the 32 years I’ve been involved in the dolomite business the most common objection when selling it has been its price.

That’s a fair and reasonable objection assuming that all magnesium inputs are equally as effective at limiting debilitating calcium/magnesium disorders in animals during spring.

However, due to reduced incomes and ever-increasing costs the priority right now is the ability of farming operations to pay their way and the price of inputs is a priority.

Dolomite is a magnesium fertiliser and unless there is a requirement for magnesium, which is the case on the majority of dairy farms, it is not essential.

The next consideration is the amount required for maximum benefit and work over many years indicates that an annual application rate of 200 – 250kg/ha annually replaces losses and largely eliminates calcium/magnesium related issues.

It is the only magnesium fertiliser that is as effective and yet magnesium oxide products have been favoured due to the lower cost per kilogram of magnesium.

The loss of muscle control and inability to stand and walk is seldom just due to a lack of magnesium.  Calcium is also involved and it’s the balance between the two elements that is essential for animals to give birth, get back to their feet and immediately produce the volume of milk required.

The Golden Bay dolomite deposit, NZ’s only, contains 24% calcium and 11.5% magnesium. It is a natural seabed deposit laid down over millions of years and due to the movement of the earth’s crust it is now available for mining.

Once applied to soil there is a steady release over time which is why a single annual application provides at least twelve months protection against Ca/Mg related metabolic disorders.

Nothing is as effective in ensuring no cows are down behind hedges at five in the morning, and now because of the marked recent increase in the price of imported magnesium oxide dolomite provides magnesium at a lower cost.

The cost per kilogram of magnesium in dolomite delivered to farms in the Canterbury region is currently around 20% less than the purchase cost of magnesium in the form of magnesium oxide.

Farmers in other regions will have to do their own calculations based on transport charges however with the recommended application rate of 250kg/ha a 30 tonne truck and trailer load is sufficient for 120ha and the delivered price may still be favourable.

All farms require an annual top up of calcium, particularly where synthetic nitrogen is regularly applied and dolomite contains 240kg of calcium per tonne, around 80% that of high grade ag.lime .

Over a 5 year period that’s the equivalent of 1.0 tonne of lime per hectare and when the value of that is added to the equation an annual application makes even more sense.

And there’s more.  Soils compress under the pressure of cows’ feet and when that doesn’t recover naturally, compaction takes place.

Compacted soils are a genuine cost with a reduction in growth often in excess of 50% for the following season.

Physically aerating the soil is an option, however a costly one particularly when dolomite, being a natural soil conditioner, may well be sufficiently effective.

Earthworms and other beneficial soil dwellers respond positively to inputs of calcium and a constant environment provides best results, a further reason for an annual light application being best practice.

Ultimately the reason for there already being such a loyal client base is the reduction in stress on owners and operators over spring.

Although autumn is the time when dolomite is most often applied a spring application will enhance pasture and milk production over the remainder of the season.

For more information talk to Peter on 0800 436 566 or 027 495 0041.

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