There are phantom traces of some crop circles. For certain people, it is proof or evidence that not all crop circles are made by people.
After the crop circle was made, sometimes you can observe - with varied clarity - that its design remains marked in the field, sometimes for weeks, for months, but also sometimes up to one or even several years after the crop circle was made.
Many investigators know that this nothing to do with aliens or "paranormal forces." It is on the contrary completely natural. But all the crop circles fans and all the investigators do not know this, and they think that it is a proof that the crop circle where it happens was made by aliens or "paranormal forces".
Here is an example of a crop circle, made in Chehalis in the USA in 1994, and photographed before the cereals were harvested:
Here is that same crop circle photographed after harvest:
What happens is that the grains that fell on the ground when the crop was flattened to make the circle started to germinate and grow.
This crop circle does not seem very "complex" nor well designed, and you can naturally doubt that it was made by aliens or paranormal forces. It really looks lame, as if done by not vvery talented pranksters.
But precisely: the "ghost images" of crop circles occur in crop circles "in general" without any distinction, because this is nothing out of the ordinary or unexplainable, it is on the contrary totally natural.
We saw that one of the causes is that the fallen grains can start to germinate and grow.
It is not the only natural cause of these phantom traces.
Among other causes, there are:
These effects can naturally cumulate.
You can notice the same effects where the crop was flattened by violent winds or tornadoes.
An objection that I sometimes heard is that it would be impossible that the traces remain one year ore more because each year, the farmers plow their fields on such a depth that trace can only disappear.
But in reality, farmers precisely do not always plow their fields in-depth every year.
You can read it here here for example: http://fr.wikipedia.org/wiki/Labour (no, this is not a "disinformation on the crop circles website"). The details are in the page concerning the Simplified Farming Technique, at http://fr.wikipedia.org/wiki/Technique_culturale_simplifiée and there is a series of articles on this subject at http://dly.free.fr/site/article.php3?id_article=54
That does not mean I claim that farmers do not plow anymore! That just shows that they inevitably do not always make an in-depth complete ploughing of their fields every year, and that they sometimes only make lines of sowing that are not very deep at all.
And of course, the phantom traces of the crop circles which are shown on some photographs are not inevitably taken years after the creation of the crop circle either and it does not happen in all crop circles.
There is also an opposite phenomenon: a mushroom, Pseudocercosporella herpotrichoides, that does not result from corns pours but causes it. This has nothing to do with crop circles, the mushroom does not make really pcreate nice designs. On the other hand, this mushroom and others can explain a "burnt" appearance of crop.
below: a crop circle which was made in wheat in Yatesbury by the same team which is at work in 2006 in Belgium, "reappears" in colza the next year. This convinced investigators that in fact "paranormal forces" made that crop circles, they find that "extraordinary":
You can do your own experiments in a garden by growing some crop and by flattening part of it to make comparisons, (you can do that in a real field but do ask for the owner's autorization!) and check all this.
Actually, a soil is a very sensitive ecological system, as all farmers know. A second crop outgrowth starting from the grains that fell from the flattened crop of a crop circle which consume the nutriments of the soil beyond what is consumed outside the crop circle explains anomalies of growth in the following cultures. A colonization by grasses, mushrooms (the mushrooms are not very visible they are primarily underground), a change of sunning and moisture conditions under the flattened crop, all that has visible effects. Those who put a kid's plastic swimming pool on their grass too long notice this easily.
These phenomena are known for a long time in ufology. Grass yellowed by a camper's tent can be mistaken for a "UFO landing trace". "Fairies rings" caused by certain mushrooms, that were formerly in ancient fairy tales alloted to fairies dancing in circles, are sometimes mistaken for UFO landing traces nowadays. Any trace of UFO or phenomenon of this kind must be studied closely before being claimed to be proof of something out of the ordinary.
Consequently, the proof that the crop circles are not all made by very human land-artists or pranksters must be found elsewhere.