that's really interesting, I cant tell from the picture provided on that page if it's man made or not but still seems a bit odd nonetheless. correct me if I'm wrong but in crop circles, I thought that the crops would grow back in the area?

As someone who has communicated with one of the leading professors in South Africa on the fields, I can tell you a small bit on it.

An idea I came up with, which they haven't gotten rid of yet, and obviously came up with long before I spoke with them, is that a large single asteroid, or a large group of meteorites, carrying material that was slightly toxic, struck the earth's atmosphere and broke into many many fragments. These fragments would have spread over a small impact radius the toxic material, and over a slightly larger radius the heat of the impact would have freed a considerable amount of trapped nitrates, stimulating growth around the rim of the crater, while the toxic area in the center would wipe out the plants, and due to the type of plants in the area would not have seeded well ever after, and would have remained bare. We have now, a field of circular impact sites that lay bare with high-growth rims.

Anyrate, she said the idea had arisen before, and there was still being testing done on all possibilities.