copper1272,I dont know why some one would tell you that you can not pour a slab on black dirt,I guess they are refering to the fact it is mostly clay and will stress a slab with contration & expanding,just get you a good engineer,problem solved, truth be known the city of Dallas is built on black dirt as you call it.

You did'nt state what you were gonna do with all this black dirt,I guess farm it ?I dont have any problem with that ole black gumbo,just a lil harder ta plow,dont crumble like some of the sandy loams do,but with the right tools the differnce is minimal in my humble opinion,maybe some one with more farming experience will give their opinion,as all I farm is hay...............good luck