Renovating a section of lawn at a commercial building. Turf got beat up bad last year and it was nothing to brag about before that. About 3-4" of sandy topsoil over what is almsot a fine gravel, no moisture holding ability at all. Infested with various weeds and very little grass so I decided to get drastic with it. Set upon it with a small disk harrow, only wanted to break up the top and was concerned about putting a tiller on it an going too deep. Well!! Got this stuff that refused to be harrowed up! Was making it about im[possible to get a good grade on it so I brought in the tiller and carefully tilled everything in. That seems to have taken care of it Already did lime and fertilizer, tomorrow I'll rake it out and spray it. But I'm curious what this stuff is. Grows in clumps with stems raidating out from the center of the clump. Very tough, woody roots which seem to run relatively shallow and are quite prolific. It's about impossible to pull the a clump up, get btoh hands under the central mas and pull until your hands hurt and finally you get the roots to break off and you get the central part to come out. Nasty enough that you could feel the tractor and tiller buck every time you got into a big clump, and we're talking a reasonably heavy machine, JD 318 with a 48" tiller.