Hmmm, I'm not too sure either. I can't quite tell what's bothering be about it..... I think it might be that you've exposed for the sky, and the foreground it a bit dark. That could probably be improved in photoshop or similar though. The foreground is also a bit empty, some of the really nice field shots I've seen usually have a hay bale much closer to the camera to have a focal point. Good attempt though, get back there and have another go before the bales are taken away!
Chris