Dutch team is pioneering development of crops fed by sea water | Hacker News Reader

Dutch team is pioneering development of crops fed by sea water

theguardian.com

125 pointsaaron69530 comments

> Inspired by sea cabbage, 59-year-old Marc van Rijsselberghe set up Salt Farm Texel and teamed up with the Free University in Amsterdam, which sent him de Vos to look at the possibility of growing food using non-fresh water. Their non-GM, non-laboratory-based experiments had help from an elderly Dutch farmer who has a geekish knowledge of thousands of different potato varieties.

This is great. I'm not anti-GM, but let's be honest: traditionally grown vegetables have a much better marketing position. Being aided by a wise old farmer is an even better narrative.

Nice idea, but what about the Elephant in the Room? How do you eliminate the buildup of salt in the soil which can ruin the farmland?

Would hydroponics be efficient on a large scale like this?

My limited experience of hydroponics tells me that it is economical for high value crops like vegetables, selling to a European or Californian market. Thera are hydroponic greenhouses which are 100+ hectare (250 acres), but for staple crops like potatoes I think it is going to be prohibitively expensive to try to grow in greenhouses with hydroponics.

If you are going to do hydroponics for veg and work with seawater then you can just as we'll go with the Seawater Greenhouse. http://www.seawatergreenhouse.com

Why would potatoes be anymore expensive than other staple crops?

Possibly but that defeats the advantage of using salt water. Efficient operations need only a small fraction of the water used in traditional agriculture.

My takeaway from the article was that this was targeted at places where sea water contamination of farmland was a regular event, or where like in the northern areas of the Netherlands, keeping seawater off farmland is unsustainably expensive.

"So nine times out of ten the salt is retained in the leaves of the plant, so you’d have to eat many many kilos of potatoes before you’d exceed your recommended salt intake. But some of the salads are heavy with salt"

Then how are the leaves disposed of, I do not know. Fed to pigs or burnt perhaps, if they were simply used as mulch you would still wind up with a buildup of salt in the soil.

Burning leaves a pile of salt. I, too, am curious where they expect the salt to disappear to.

If you burn it, and have a pile of salt, it might be possible to remove the ash and keep the salt.

Burn the leaves and use the ash in artisanal soap?

Maybe they can just dump them back into the sea.

Salt is worth money. If you have a bunch of salty leaves, you should be able to process them and get the salt out.

Might cost you more money to get the salt out than you can sell the salt for, though.

Just dump the leaves in the ocean. Biodegradable and the salt came from the ocean anyways. The leaves if too concentrated will intake a lot of water and their cells burst. Or the leaves won't be too concentrated and will be eaten by nature.

Maybe they should bring the crops to the sea rather than bring the sea to the crops.

I've been wondering abut the viability of farming in floating polytunnels. They could even be temporarily submersible to weather storms.

How would a polytunnel be submersible? A poly tunnel is a really flimsy structure. Just going down 10 meters double the pressure (1 bar), and being any shallower isn't going to protect you from the surface water churn. Not to talk about the effort to push thousands of cubic meters of air under water. Not very practical I don't think. :)

Polytunnels are flimsy in compression, but clear plastic can be very good in tension and can contain a bar or so of pressure fairly easily, so it may be feasible. It was only one of the solutions I thought of for coping with storms if you are growing out at sea. The other two are either being able to reel them back onto land, or just making them short and tough, so they can just roll over the waves. The buoyancy problem isn't that difficult though as you can have counter-buoyancy that rises when they sink.

Building a submarine out of a polytunnel just isn't going to work. There are so many better ways to spend money. There are literally many thousands of km of dessert coastline where we can build greenhouses and grow vegetables where nothing else can grow. See my other entries in this thread.

You grow these GMO tomatos which thrive in salty soil and actively remove the salt by concentrating it in the leaves http://www.newscientist.com/article/dn1092-genemodified-toma...

What happens to the leaves? Do they also get harvested?

In the end I think you will get a salt concentration somewhere. Your compost may not be so usable for example. You provably have to be careful where you put it if you are dealing with any significant volume.

The leaves of the tomato plant are poisonous, even before you think about the salt.

A lot of Dutch farming in greenhouses is already hydroponic, i.e. Little or no soil is involved.

There are very few species that have a high tolerance of salt, thus the idea, although good, has a limited range of uses. If you wanted to transfer the salt resistance of a potato to a lettuce you would need to use DNA splicing, making it a GMO. Also, it is true that most of the salt is retain on the leaf, but a good portion remains on the soil as small crystals, accelerating erosion of the field.

My parents visited his farm a few months ago, and told me that the potatoes don't taste salty at all. "Just like normal potatoes," they said, "they needed a little bit of salt added after baking for the taste." I'm hoping to visit it myself, if I have the opportunity next spring/summer. It's quite a spectacular start of rethinking food, imho.

Wouldn't it make more sense to just improve desalination efficiency? This sort of biological engineering is a lot more difficult and has a lot more ecosystem-wide effects than improving desalination would.

Increased salinity of soils is a big issue anywhere where groundwater is used for irrigation and there isn't much rain. Literally hundreds of millions of hectares are affected. [1]

We are probably going to have to attack the problem on many fronts simultaneously. If we could get efficient solar powered desalination, or something based on nano materials, that would be great [2], the current RO process is fairly energy intensive.

But you still have to deal with brine, and that is hard unless you are close to the sea. And if you are close to the sea and in a hot area, I'd personally go with Seawater Greenhouse technology instead. It has many side benefits, albeit probably not suitable for staple crops. [3]

[1] http://en.m.wikipedia.org/wiki/Soil_salinity#Salinity_due_to... [2] http://www.kurzweilai.net/selective-nanopores-in-graphene-dr... [3] http://www.seawatergreenhouse.com

Actually I think breeding salt tolerant plants would be significantly easier than trying to improve desalination. Although we still have the solve the problem of salt build up. But perhaps it will be easier to remove it from soil and plant matter than from water.

In any case the immediate application is to use it places where the soil is already salty. Better desalination wouldn't help there.

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