Advice needed on painting African red soil

[cram]

Hi,
I'm basing up some Zulu's I've recently painted. I cant create a red looking soil that I'm happy with the look of though! If anyone can offer me some advice on how to paint a convincing looking red soil I would be very grateful, as this is really holding me up.
Many thanks.

[Bugsda]

A wash of burnt sienna works for me.