Did you make the wheat too? They look great. Plants are actually more challenging than hard objects. And I agree with DecanAndressen, the soil texture really ruins an excellent piece of work. Also, some broken wheat straws stuck on the front would really give it a twist. It kind of looks like it fell off an airplane now.
Very impressive. There is only two things that gives it away as 3D. The ground texture and the clean wheels. If it wasn't for those two things, i wouldn't be able to see the difference from a real photo.