thanks for your comments. The lens is the Sigma 10-20mm ultra wide angle. This is one of those very rare occasions where the land was just about the same brightness as the sky. No ND grad filters were used - just slight adjustments in photoshop. Shadows lightened a little and the luminosity of the blue sky darkened slightly, plus contrast and saturation increased a little.
Generally, I bracket exposures for land and sky (3 exposures usually or more if shooting directly into the sun), then comp them together in photoshop using layer masks. ND grad filters are fine but not always ideal and I find that photoshop gives me more control over the final image.