I saw another Redditor post this in a comment and my bullshit indicator started wavering. I want to know if this is actually how deserts form. X-posting to /r/AskAnthropology as well.

It might be interesting to note that irrigation in agriculture leads to a slow build up of salt. Water is spread out and allowed to evaporate, leaving behind the trance amount of salt that was dissolved in it. Over time this leads to salinity which regular crops can't handle. This happened in the "fertile crescent" of the middle east. Farmers started growing barley (a wheat substitute that's more hardy to salt than wheat itself) to cope at first. But this only worked until the tolerance level of barley was exceeded. The net result was the creation of the desert like conditions that are now wide spread in the middle east.

The only form of agriculture that doesn't lead to this multi-generational problem is the water terrace system used by the Chinese and in the past by the Incans.