The last article focused on information from a letter written by the late Les Hawill to a farmer client in the Waikato. He claimed that with increased use of dolomite “the economy could bloom like never before.”
That claim may at first seem somewhat extravagant, however, when a single farm meeting their magnesium demands with the use of dolomite is looked at with a focus on the increase in pasture growth, the reduction in animal health costs, and the improvement in animal weight gains and production, multiply that by the number of farms in the South Island alone, the claim appears a great deal less bold.
There are 4 major cations measured in soil tests, calcium, magnesium, potassium and sodium. The levels of each are important however it is the ratios of those elements that are probably most important.
The ideal Base Saturation figures are Ca 68%, Mg 10 – 12%, Potassium 3 – 5%, Sodium 1 – 2%.
Sodium is not a plant growth requirement, however, it is essential for optimum animal growth and performance. Several important pasture plants including brown top, red clover, paspalum, and kikuyu are classed as Natrophobes (sodium hating) and have very low concentrations of sodium in their leaves with maize the lowest containing only 0.01% of sodium in shoots and stubble.
Sodium supplementation is therefore essential where these plants make up a significant part of the diet and the most efficient means of ensuring each animal gets sufficient sodium is to have salt in the form of blocks available at all times. Animals self-regulate and immediate high demand normally reduces within a few days.
Les Hawill after years of experimentation recommended that salt not be applied to pastures in a solid form as its effect in lifting plant sodium levels is short term only and it has the ability to reduce iron, zinc, and copper availability.
Due to its effectiveness dolomite is also increasingly being used as an animal supplement. All animals that are deficient in calcium and /or magnesium within a few days identify dolomite made available in a convenient container and readily help themselves and the work with farmers to date indicates that stock do self regulate.
It is essential when making minerals freely available to stock that they are not mixed, or mixed with feed supplement, and a plentiful supply of clean fresh drinking water is also a requirement.
The dusting rates to pasture of dolomite have not been accurately ascertained. To achieve an even spread of any dusting material is virtually impossible. Efficiency is hard to achieve as each animal’s requirement is different and changes depending on weather, amount and type of feed, and stage of pregnancy.
The fail-safe and therefore preferred method of minimising calcium magnesium related metabolic disorders this spring is to apply dolomite at approx. 220kg/ha and have dolomite available in containers at all times both prior to and after calving.