Tidal mudflats don't seem to accumulate salt in the same way evaporative salt ponds do, since the water is not trapped allowing for concentration. So maybe something where tidal water is allowed to flush out overly saline water would work?
I think on hot days you are supposed to "flush" the rice fields with fresh (cooler) water anyway. The runoff then goes back to wherever (a river or in this case maybe the ocean). Assuming that is true, I imagine that means any relevant nutrients are not flushed out by this process.
