If you're going for closeup detail, it might be best done by hand, depending how close, any way you look at it, you'll want to model your grass by hand, and then duplicate it either with particles (preferrably, if u want to burn it

) or manually, or with scatter or shag or whatever.
Model the grass with however much detail u want, and maybe do lower quality, polygon n texture wise for the distance shots and for areas that arent viewed up close.
should work a treat.