Thanks, everyone. I gathered as much about the colour/brightness.
I have a second render on now that I've just edited, hopefully with better colour.
In the first one, when I look at it now, the colours between mud/birds seems kind of backwards. I wanted a nice dark brown mud but it's lacking a little red tint, whereas, the birds are appearing slightly reddish in comparison to this brown. I think I've fixed this now by adding a slightly red layer to the mud and making the birds a bit lighter and more of a flat brown. I'll see how it goes soon, it's only taking about half an hour to render this view so, no big deal about time.
There's also a little more tiny displacement now and the depth of the furrows is slightly less, as TU suggested. Post soon.
Ulco: Not actually sparrows at all, they're robins! I edited the texture because we rarely see robins around here when the fields are being ploughed and crops sowed. It is quite a nice little model that I wanted to use, any other little birdies I could find weren't up to the task of being this close to the camera.
Bob: I don't think that dunes would look very nice with this method. It is really just one long simple shape shader, replicated by a shader array node across the width of the image. Dunes would be far too repetitive, I think.
The furrows weren't really what I was working on, I just popped them in there to give the mud layer some extra features, other than a flat surface.
Cheers, all!
