Since I've got your attention on this (thank you), can you advise how you would select and area that you wanted to adjust with contrast etc? I used the magnetic lasso and feathered it about 50-100. But after adjustment, I then went around the edges of that area to blur it as there was a fairly obvious line between the two sections. I also cloned some of that grass on the very top of the bank to stamp over the edge area, as there it was rather obvious between the two sections.
Here is one way to do what you are asking.
Create a copy of the scene in the layers pallette.
Adjust the whole new layer for contrast, etc. paying attention only to the area you want changed. IE the rest of the image may blow out, lose details in the shadow, etc...
Then control-click on the add layer mask button on the layers palette (assuming you use windows). This should effectively hide the adjustments you just made and make a black layer mask attached to the layer (visible in the palette).
Then, with the layer mask selected, use the paint brush tool with the color white selected, with a hardness of about 50% (or less), this will give you a feathered edge) and 'paint' the adjusted area back into the picture. And it should blend in wonderfully.
If you don't understand this or can't follow it (and don't worry, I'm a horrible technical writer) private message me and I'll give you my email. You can send me the psd file and I'll create the layers and everything as an example and then you can see it in action
I got stuck when it came to painting with the brush - white paint just covered where I went. Obviously not quite right. Perhaps I had the mask wrong?
Here's a screen print of how far I got. You can see my white splotch in the middle of the cloud. Advice welcome.