Salt Block Weathering


Imported Rock Salt vs Summit Rock Block Weathering


Note:  Summit HARVEST Salt Block is the same product as Summit ROCK Block.  Packaged as:

salt blocks

ROCK Blocks are packed in an individual carton


Harvest Blocks are uncartoned, packed in a safety sling


 In 1990 MAF conducted trials on block weathering at TaraHills and Ruakura Research Stations.  For a number of years farmers had been claiming that rock salt weathered at a slower rate than pressed salt blocks.  When Dominion Salt developed Summit Rock Block as a longer lasting product its weathering rate was tested against imported rock salt.  The blocks and rock salt were exposed to the elements and protected from stock. At regular intervals the salt remaining was measured and the weathering loss calculated. The results were conclusive – at Tara Hills Summit Rock Blocks lasted 1.8 times longer when exposed to weathering elements, and at Ruakura they lasted 3.8 times longer.  Summit Rock Block sustained twice the rainfall before 50% of the salt was lost to erosion.  At Tara Hills, at 100 days 35% of the rock salt had been lost to weathering compared to 15% for the Summit Rock Block.

 The weathering trials were done in cages so that stock could not access the salt.  When stock are offered imported rock salt and pressed salt blocks in the same grazing areas it is observed that the rock salt lasts longer.

Points to consider:

    • Differences in disappearance of rock salt and salt blocks in a paddock arise from palatability and stock preference, not weathering
    • Because salt is soluble there will be weathering losses. Accounting for weathering losses you would need to purchase 20-30% more rock salt compared to pressed salt blocks to get the same amount of salt into your animals (based on salt at Tara Hills being out for 100-150 days and approximately 75 days at Ruakura)
    • Summit Harvest Salt Block is the least expensive form of salt lick in the Summit range


Rock Block weathering graphs