Thanks! I'm not 100% what you mean though. Do you mean where my grass goes into the brown fields? Essentially to do the grass I just rendered some plasma over a green background, extracted the grain and then washed out the saturation, and then made it sufficiently transparent to see the green through it More than likely this is the wrong way to go about it!

I also struggled to do any contouring, without having the PS layer styles as described in Larb's tut.