Salt makes most crops fail to grow. So why is the land that the Netherlands reclaims from the sea — which has been under salt water for ages — useful for agriculture?
In: Biology
When [Danube – Black Sea Canal](https://en.m.wikipedia.org/wiki/Danube%E2%80%93Black_Sea_Canal) was built, they transported the dug out soil all the way to Netherlands to be used in reclaimed areas, as it was really fertile.
First, you will likely need to bring in soil anyway. There isn’t much substrate that is under the ocean and that you can use to plant food-producing plants in. It’s generally sand, or mud, or gravel, or solid rock, or clay… and removing salt makes clay get even worse. So a lot of the soil would simply be relocated from elsewhere, and can be amended with strategies like piling up seaweeds above the tidemark and letting the rain wash the salt out of them before plowing them in.
Second, the salt actually IS easy to remove for any reasonably viable soils that you can use that have been uncovered. Simply wash the soil by diverting a fresh water source to flow over and through it, or to soak on it as if it’s a pond, and use effective drainage to let the salt-containing water flow away. Eventually the salt washes out, perhaps even through natural rainfall if you have good drainage and enough time.
Next, there are additives like gypsum that can help better remove salt as you wash that soil.
Finally, there are salt-resistant crops that can help deal with any residual salts after this sort of treatment. China grows salt-tolerant rices in tidal basins, for example.
So it’s a mix of strategies, with the biggest factors being the bringing in of soil to replace the poor stuff that damming might reveal, and the washing out of the salts of anything usable that’s left when the ocean water recedes.
[https://edepot.wur.nl/211289](https://edepot.wur.nl/211289)
“When the muddy deposits have accumulated sufficiently to rise
above the normal summer tides, the salts are consequently washed out of the
upper 20 to 30 cm. of the muddy deposits by the summer rains to such an
extent that the original salt vegetation (Seaweed, Salicornia, etc.) gives way
to a grass flora. These grass-grown deposits are called “kwelders”; they are
covered only by the high tides, especially in winter. When the kwelder is
high enough a dike is built to keep out the sea water; the kwelder is now
transformed into a young sea-polder.”
In the East of England is an area where they did similar, silt is deposited in The Wash each tide, so you build sea walls with lock/sluice gates that let the water out slowly after a high tide to capture more of the silt. Then when you have enough soil, and if there is more silt building up at the water line, you build another wall further out to start capturing the next area
Silt is naturally very fertile soil, but the salt content is too high for most crops, so first they grow types of grasses like samphire which are salt tolerant… After a few years less salt tolerant plants can be added and over time the salt tolerant plants get out competed and you progress to normal soil with normal salt levels which is very fertile and can be used for growing normal crops
I’ve also seen in Dutch universities they are working on crops which are more salt tolerant, potatoes for example which are sweeter in order to survive in the extra salty soil
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