If you are interested, may I suggest you follow the patterns on Google Earth, and when you have covered enough territory way beyond that one salt pan, and you find that the patterns change shape and go on forever...you’ll forget all about the farmer and his tractor.
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Has this been studied by scientists or just bloggers?
A lot of this 'stuff' is the result of people using Google Earth. There aren't enough scientists with enough funds to follow all of it, not if it can't be attributed to global-warming. How about the contour irrigation images from South America? You can find them yourself:
