Dominion Salt

Common salt, sodium chloride, is essential for optimal livestock health and production in many regions of New Zealand where sodium chloride is deficient in soils and pastures. The usual methods of supplying salt to animals are in salt blocks for licking in the outdoors, and through loose salt supplementation of silages, feeds, crops and water sources. Since the 1940’s, Dominion Salt has provided most of the needs of livestock in New Zealand through Summit Salt products, originating from Lake Grassmere, Marlborough, and from the Dominion Salt plant at Mt Maunganui, Bay of Plenty. All product forms come with added mineralisation where required.

Dominion Salt is jointly owned by Cerebos NZ (a subsidiary of Cerebos Pacific, the Singapore-based food and health supplements company) and Cheetham Salt of Australia, which is in turn owned by CK Life Sciences, a Hong Kong China company. It has an annual turnover around $20 million and employs 50 to 100 people depending on the season. Its agricultural division is called Summit Salt.

Solar salt has been produced at Grassmere in Marlborough since the 1940’s, pumping in sea water (2.5% salt) to large lakes and then concentration ponds where sunlight and wind produce evaporation. When the brine reaches saturation point it is transferred into crystallisation ponds during the summer months. The salt’s crust is lifted from the bottom of the crystallisation ponds and transported to one of the two washing plants where it is washed in brine before being stacked in piles. The stockpiling is necessary because of the seasonality of production. During the refining process, the salt is rewashed, crushed, dried and screened before being packed in 25 kilo bags, or bulk bags containing 1-1.2 tonnes.

Salt destined for the domestic table salt market accounts for a very small fraction of the harvest. Production at Grassmere is 60-70,000 tonnes a year, depending on weather conditions, and solar salt accounts for about 70% of Dominion Salt sales.

Lake Grassmere saltworks was founded in 1943 by Christchurch entrepreneur George Skellerup, who also founded the Para Rubber Company. It produces about half of NZ salt requirements.

Dominion Salt operates a vacuum refinery at Mt Maunganui, first installed in 1973-74. Vacuum-refined salt is higher purity than solar salt. It is produced from artificial evaporation from treated pure brine in a near vacuum. Solar salt is dissolved and treated with chemicals to remove impurities. It is then evaporated to a super-saturated solution, from which crystals are removed in a slurry and then dried. Vacuum refining has allowed the company to develop a wide range of salt grades to meet the needs of the dairy, pharmaceutical and food manufacturing industries.

Common salt (sodium chloride) is an essential constituent of animal diet. Because many New Zealand pastures away from the coast are deficient in sodium chloride, some form of supplementation is often necessary. For instance, lactating cows need a daily minimum of 20grams of sodium chloride, dry cattle a minimum of 10g and sheep a minimum of 2g.

Sodium is routinely expelled from the body in milk, urine, faeces, sweat and saliva. Sodium chloride should be available to farm animals every day and because of this, is a convenient carrier of other minerals. New Zealand grazing pasture is most susceptible to deficiencies in cobalt, copper, iodine, and selenium. Zinc supplementation is also important for immunity and hoof health. Trace mineral deficiencies may induce problems such as abortions, retained placentas, mastitis, and infertility.

Summit Salt is the number one agricultural salt brand in NZ and has been around for generations. Minerals are added for specific livestock needs. Blocks of salt are formed by pressing, including non-mineralised Rock Blocks and a range of mineralised blocks. Compact 20kg Summit Salt Blocks are easy to stack, handle and dispense. Trials prove Summit Salt Blocks last nearly 4 times longer than loose rock salt and require twice as much rainfall before being broken down by the elements.

Summit Multi Mineral Blocks have added copper, zinc, iodine, iron, cobalt and selenium, and are suitable for dairy cattle, beef cattle, sheep, deer, goats and horses. Other Summit blocks have specific supplementation with magnesium, copper, zinc and iodine for targeted animal needs.

Summit AgSalt comes in 25kg bags of either coarse or fine loose forms, suitable for mixing in water systems and for supplementary feeding with hay, silage, meals, lucerne, red clover, kikuyu, paspalum, maize and other crops. In the same format is Summit Dairy Multimix to be added to silages or grains and containing zinc, cobalt, iron and selenium. Another product called Magmix provides sodium and magnesium for lactating cows (to help prevent grass staggers and milk fever) and one 25kg bag would provide the recommended daily intake of 70g/day to a herd of 357 cows.

Summit Amaize is a loose salt in 25kg bags formulated to provide salt, magnesium oxide, lime flour and molasses at the recommended feeding rate of 200g/cow/day. It is for supplementation of maize silage, which is particularly low in sodium chloride. Maize is a natrophobic plant that does not take up salt from the soil even if the soil has good salt levels. Another natrophobic plant is kikuyu, the majority pasture cover in Northland during summer.

In recent times Dominion has developed lifting slings for Harvest Salt blocks which lessen manual handling and improve safety when handling pallet lots of blocks. Harvest Blocks have no added minerals and are particularly hard weathering. They are only available in the slings, containing 30 x 20kg blocks. This form is most useful for year-round salt availability on all paddocks, at the rate of one block per 10 cattle stock units and one block per 20 sheep stock units. The lifting sling handling has taken on added emphasis with the new health and safety legislation and the campaign to reduce injuries and accidents on farms.

Bigger salt users in the hill and high country buy and distribute tonnes of salt blocks each year around farms.