cayugad pretty much summed it up. I echo the sentiment about brushing it in. It does make a difference.
I will play devil's advocate just for the sake of it. I do about 90% of my hunting from the ground. Just a small portion of that is from a blind. I have been backing myself up against a tree since I was 8 and have had very good success at it. I feel limited in a blind simply because of the impediments of the windows. When I sit on the ground, that goes away and I can see much better. I also feel like I can hear better outside of a blind-and I use my ears more than my eyes when I hunt. Then again, I hunt the woods and not fields so that may not be applicable for you.