Wonderful idea, and good composition. I would suggest metering for the sky to avoid the sky from looking so blown out. If you have a DSLR - try a graduated neutral density filter - you can selectivley darken the sky, but keep the same exposure for the trees and field. While I know you can do this in photoshop with the filters feature, you can also do it 'in camera' so to speak.
I really like your crop here. Maybe a different time of day to give you a more interesting sky. Granted, that is a small detail (but for some reason on DPC, a good sky is a major factor to some voters).
nice idea ... think it would have been much more dramatic if you had shot it at sunset when the light is much more appealing. That would have darkened up the sky , brought up your saturation and given the hay bales a richer color.