How can I break down SOLID clay soil that is underneath sod?
Spread gypsum powder on the lawn and water it in. Gypsum is the white stuff they make drywall out of. But, you can get 20-pound bags of the powder in the garden center of a home improvement store. Spread it on about 1/4 inch thick (like a light dusting of snow) and water it in. Water for about 5 minutes each day to wash it down to the clay layer. Every 3 days or so, give it a good soak (20 – 30 minutes) to soak it down into the clay. After a week, add some more and repeat the process. I had an area of dirt where a slab was removed during a remodel and it was solid clay (the consistency of modeling clay). I couldn’t even dig it out with a shovel. I did the gypsum thing described above and, after two weeks, I was able to till the soil down to 6 inches with a 4-tined metal rake. It was amazing how well it worked. Keep in mind, though, that a 20-pound bag ($10 to $15) only covers about 50 square feet. So, you’re going to need *lots* of gypsum. But, it’s certainly cheaper than resodding the
