So, I was looking at some satellite photos of the tsunami after effects. (check out the link, really neat before and afters) And I noticed a lot of the before pictures in Indonesia seem to show little farmland patches. I’d always heard “salting the earth” will prevent things from growing there. Has being flooded by salt water ruined the soil? And if it has, how long before you can farm on that soil again?
The amount of salt dissolved in sea water would not normally be enough to destroy the ability to farm a particular field, particularly since most of the salt will have receded with the wave, still dissolved in the water. Further, any rains that follow will dissolve the salt further, adding it to runoff into the sea. (This is not to say that no salt damage has occurred, only that is will probably not be among the worst problems the survivors face.)
The Dutch have reclaimed thousands of hectares of land from beaneath the ocean and turned them to farms. While there was a period of desalination, this was to compensate for the lands being below the ocean for thousands of years.
Looking over the photos of Banda Aceh I see areas that appear to have been recovered land from below sea level that are still flooded. Those very likely will suffer salt damage, but as they have already been recovered and farmed once, I would expect that they could be recovered and farmed again (providing someone can afford to rebuild the dikes and levees).
On some of the smaller islands, there is a problem with saltwater draining through porous limestone into the fresh water supplies. This will likely render some islands unihabitable.
When the East Coast of England was flooded by the sea in 1953 it did take a few years before the land was fit to grow crops . I think that after three years they started with cabbages , which are more tolerant of salt . It was another few years before cereal crops could be grown. Here are a few quotes from an article I found on-line
" salt water killed virtually everything, plants and animals, years before earthworm seen again
farmers given grants, land had to stand idle for three years, gypsum put on soil "
In addition to the seawater, the tsunami left many areas covered with mud from the sea bottom. That mud is also saturated with seawater.