The sun's pretty far to the left; could be a sunrise/sunset. How bout adding some tinges of orange or pink?
Even when it's midday, the sky isn't made of one solid color; it gets brighter near the horizon.
If you notice, in your reference picture, the closest rice plants can be seen clearly, while the farther ones group together to create texture. Try to show that depth - right now I just see lines that are all of the same width.
I'm also going to say your green is too bright.
Great start!
