Nope, all of these photos are "real." Many times, farmers will "cut-out" messages in their fields for planes to see. Nowdays, farmers also do it to be seen on Google Earth, like the four you have found. I don't speak Chinese, so I can't tell you what they mean. (Does anyone know?)

One of the coolest stories I have ever heard of on Google Earth is a personal ancedote regarding these crops signs. You can read it here.