Ghost Crop Circles: It's that their signature?

Ghost Crop Circle: is that their signature?. Many Crop Circle left on the ground something that do not allow the crop to regrow. After several years, the ghost of the formation still reappeared and in some cases the new formation is made exactly on top of the old one. If they are man-made, are they spraying something in the ground to let their signature? I want to know what type of board and rope they used at this formations. When are going to accept that we are missing a very powerful information at this data base bank?

nice video, a couple of those i have never seen.
i am just wondering, there are heaps of these crop circles, why has never someone got caught, building these circles.
i mean, like robberies, a certain percentage in statistics does get caught.
never heard of people got pinched doing crop circles, weird.
at least statistically they should have got one of them.