In addition to good compost, you might give Medina's Soil Activator a try.

"LeeBoGene" wrote in message
...
Once one gets started removing construction grunt, sheetrock, shingles,
and metal crud from the garden, what does one use to soften the sand
clumps and hardpack? Bentonite? When one works with a pick axe, it's about
time to add some heavy duty soil softener.

But what? Any mud engineers out there with a clue?
Thanks.