I've never been able to get a really great stand of it and think it's due in part to what REN states above; it really seems to like sandier soils. I'm continung to experiment in different areas of the farm till I find one that works well.
Last year one of my plantings of about 3/4 acre was almost completely scratched up before it even germinated. Freshly disced dirt and newly planted chufa...might as well be ringing a dang dinner bell.