Betsy Mason of Wired Science has a really neat post about how farming in various countries create strange agricultural landscapes as seen from above. This one above is from Libya:
The lonely green circles in this image are center-pivot fields 0.6 miles in diameter in southeastern Libya near the Egyptian border. Known as the Al Khufrah Oasis, the fields are one of Libya’s largest agricultural projects. Virtually no area of Libya receives enough rainwater to grow crops, and the fields here are irrigated with water from an underground aquifer. The image was made by astronauts aboard the International Space Station on Oct. 28, 2004.