Back in March, before our new home was built I got a soil test. The soil was high in potassium and surprisingly high in calcium and organic matter. I believe my property some years ago was a farmers field, so I could account for a 5.3% OM, but I was surprised by the high calcium reading. The last two weeks I started working on the front yard landscaping and there were a lot more of the pot rock in the backyard. I figured this rock to be limestone, but I wasn't sure until I found this yesterday.