Oh they do revisit the sites, IF the farmer will let them !
The farmers in Wiltshire are sick of crop circles ruining their crop and all the people walking across their fields !.....apart from a few of the more enlightened ones. A whole new business has sprung up with people selling seeds from "affected" crops.
Theories abound and no one has a definitive answer but there is no doubt that with genuine crop circles the land and subsequent crops are affected for a number of years after.
Actually this is a good point these echoes of formations still shadowing the earth. The fake ones done by man by stomping would not leave an impression years later. So yes something literally changed the compostion of the dirt.......this is reassuring to me about the authtenticy of it all....pretty cool indeed.
The article is a translation from Spanish into English so it's a little difficult to get through the slightly muddled English. But the explanations presented (along with photos) do make sense. At least now I have pretty good understanding what we're actually seeing in these "ghost" images and why they appear as they do. Pretty much takes the mystery out of it (hate it when that happens) but I just had to know.
Quote from the article:...the decomposition of the “straw” (I mean the remaining of the flat plants) becomes a strong fertiliser penetrating in the soil at a considerable depth (this is a data that we will have to remind further).
What the writer is saying is something like this:
1. The crop gets flattened to form the original crop circle.
2. In some cases the field is not harvested (for whatever reason).
3. The unharvested crop withers and dies.
4. The soil where the crop was flattened (the crop circle) has become more fertile than the surrounding soil because the flattened crop (virtually laying on the ground for some time) has decomposed, thus causing that soil to undergo chemical changes that the surrounding soil didn't get. The chemical changes virtually act as a fertilizer.
5. The more fertilized soil then becomes a host for weeds which, of course, now grow in the shape of the original crop circle while the rest of the field remains essentially baron of these weeds.
That's an explanation for fields that were not harvested. The explanation for fields that were harvested is somewhat different yet similar. Basically (at least as I understand it) in every case the "ghost image" that we see is ground cover type of plant/weed growth in the areas where the crop was flattened to the ground.
So, if these explanations are correct, then the photos of the fields where the "ghost images" appear must have been taken either after the field was harvested or after an unharvested field was allowed to dry up. Although I suppose the "ghost" image might be visible (from the air) in a field of unharvested new crops, too, if weeds are growing among the new crops in the soil where the old crop circle was laid down.
Is that all as clear as mud? LOL! I dunno. I'm just trying to explain what I think the article was saying. :-)