On Soils and Dry Coasts

I studied soil science as part of my geology degree. I aced the class because it was fascinating. One of the points brought up is a common sequence that occurs in Archaeology regarding soils.

1. Few cultures learn how soils work before ruining them. 
2. The best soils grow grains, so meadows/plains/deserts have the best soil, not forests. Forests and orchards tend to have bad soils. 
3. Soils that won't even support trees are often infertile, dead things. This would include sand dunes and bare rocks. Most of the middle east and parts or Ireland Scandinavia are like this. 
4. One big cause of soil infertility is lack of proper proportions of materials to make good soil, and lack of microbes in that soil. Very cold places often have bad soil because it is too cold for the microbes, and the chemical breakdown of clays and silt never happens so they end up useless for plants. 
5. It is possible for fertile soil not to grow plants when rainfall is too low. This explains many desert soils, including in the Sahara and Mohave deserts. Even modest increases in water supply causes massive fertility and plant growth. Deserts breathe as their oases swell, and die back when they retract. The El Nino and La Nina events have been going on for millions of years and both deserts have evolved to take advantage of these, or resist their worst. 
6. Irrigation from non-conventional means has produced fantastic agriculture production in California and parts of Mexico, and is the primary reason for construction of major dams. 
7. When soils are abused too far, few cultures learn how to fix their soil in time and end up turning to the sea for sustenance. This is often fatal for a large percentage of those who venture there, so cultures that give up on the land die out for the most part. 
8. Cheap desalination could restore arable land from dry coasts like the west coast of Saharan Africa, Namibia, Baja California, and the dry Chilean coast. It would also offer tremendous value to most of Australia, though many areas need better soil to justify desalination costs. Experiments with mechanical windmills driving vacuum pumps to assist in evaporation of sea water brines into fresh water, dumping the brines afterwards back into the sea, are iffy and expensive. They may be a way forward, but maintenance costs might prove this unfeasible. The Altamond Wind Turbine debacle has shown that coastal wind surges cost more to repair than the product of years of stable operation are worth. 

I do think that eventually we'll see cheap desalination because drinking water is valuable and converting it from salt water is SCIENCE! Modestly priced desalination would still work, but cheap has a lot more benefits because more poor people can afford it and your can use it on more things. If there were Monaco type towns every 20 miles down the coast of Baja Mexico, on both sides of the Peninsula, plus the mainland that's around 4000 miles / 20 = 200 Monacos. 

Imagine one of these every 20 miles from Canada to the tip of Baja

Perhaps diluted by different focus, as there's such a thing as too many casinos, but if each were running useful businesses and port facilities? Wow. That's better than most of Mexico has now. And its mostly empty at this point, just bare desert rocky shorelines, exactly the sort of place you would want to construct a jetty and harbor for commercial and sailing boats, and commercial sail-powered fishing boats. If you used a sail to push around a boat, and solar panels for water and ice, even if the wind dies you're still okay, especially if you run an electric motor off those panels to get home if the mast breaks or something like that. Electric winches and proper design can take classic galleys and other ships designed around a sail and cargo hold and make that work. 

It won't look like this, but simple single mast sailing ships and modern electric winches with a computer to help control them? That's possible. Add radar and radio and onboard desalination and you can fish quite a lot of the ocean, though cold water holds the most nutrients, so cold water with good sunlight makes for the best fishing grounds: thus California and Peru have the best fishing in the world. We've abused it, but if fishing was only licensed in those areas for sailing vessels, the time it takes to make new boats to meet the licensed higher catch limits would give the fish long enough to recover their numbers. The Coast Guard and Navy would need to arrest or sink any crews with illegal boats however, which is a bigger problem. Japan and other nations cross the ocean to steal fishing well over the limit and then cruise all the way back for big profit. This harms US here, and local fishermen rely on the fish to make their living and pay the costs of their boat loan and wages for fishermen. I'd want to learn a lot more about this. The important thing is it is possible to have a viable city on a coastline with cheap desalination and your protein from fishing without using any diesel fuel. A nice future is possible.