I have planted some of thier "ALFA-RACK PLUS"in the past on a slight slop and it did pretty good. Lasted into a couple yrs despite dry and hot summers. I have planted another small bag of it this yr in another location to try and see how long it will last, hopeing to get 3-4 yrs from it. I limed the spot real good back in March put 1 ton (2000lbs) on 1/4-1/2 acre. I planted it Oct. 7 2009.
So maybe it will last for a while. The dirt is mostly sandy.