Saltwater corrodes firefighting equipment and may harm ecosystems, especially those like the chaparral shrublands around Los Angeles that aren’t normally exposed to seawater. Gardeners know that small amounts of salt – added, say, as fertilizer – does not harm plants, but excessive salts can stress and kill plants.
“Salting the earth” was done by conquering armies who weren’t going to try and occupy the region.
It can turn fertile fields barren for years, and there’s not really anything you can do about it.
There’s very little evidence that ever actually happened, though it’s possible it did happen on rare occasions.
Its quite likely it was known about but not done due to the time, cost and availability of salt to an army out of its territory.
Probably it was always a bit of a metaphor, just like we use it today.
I mean, salt was expensive as fuck, people weren’t wasting it to fuck over someone very far away…
Most of the time it was a symbolic gesture with like a hand full of salt.
Dumping sea water at this volume tho will have an effect for a long time, and we can’t really undo the damage. Which is why it’s an apt reference.