Much of the conventional fertiliser model is based on the premise that the cheapest input is the best. This ignores the performance aspect of products and there are many examples where the cheapest products available simply do not perform as well or provide the range of benefits of more expensive products, whether it is water pumps, spades, or tyres.
The reasons “that it’s what everyone else does” or “that it’s the cheapest per kg of nutrient” are inadequate because they fail to answer the question of “what’s in it for me?”
What is important is what you get for your money, and what you get is called performance. When it comes to magnesium fertiliser Golden Bay dolomite is not the cheapest provider of magnesium, however if the reason for applying magnesium is to limit the number of animals suffering from lack of magnesium, the performance of dolomite is without equal.
Dolomite is also a provider of calcium and this sometimes seems to cause a degree of difficulty. What dollar value can be applied to the magnesium content, and what value can then be attributed to the calcium content?
The reason animals suffer from calcium/magnesium related metabolic disorders in spring is seldom due to either element being deficient, it is usually the imbalance of calcium and magnesium which is one of the reasons dolomite is so effective.
Dolomite typically contains 11.5% magnesium and 24% calcium. Soon after application there is a lift in plant leaf magnesium to between 0.22% and 0.25%, with the calcium content of grasses remaining at around 0.60%.
When animals are fully fed on high quality pastures with this balance of magnesium and calcium, and there is sufficient fibre for good rumen function, calcium/magnesium related metabolic disorders are seldom an issue.
Over summer plant available calcium has a major influence on which pasture plants grow strongly and how much total pasture is grown. Clovers are ideally suited to growth over summer as they thrive on more sunlight and higher temperatures.
Clovers are usually 3 to 4 times higher in calcium than grasses, and being more digestible, animals are able to physically eat and digest more feed and therefore produce more, gain weight or grow more rapidly.
High performing dairy properties require a minimum of 200kg calcium per hectare per year for optimum performance. Dolomite applied at 200 – 250kg/ha provides 23 – 29kg magnesium per hectare and 48 – 60kg calcium per hectare.
To provide the extra calcium required for optimum clover and total farm performance requires a further 500kg/ha of high quality ag.lime annually. When dolomite is applied annually at the rate required to meet magnesium requirements and sufficient calcium is also provided, damage to clover by flea and weevil is minimised. Yet another advantage!