Does adding a particular rock, such as limestone or granite, actually alter the planting medium of a trough in the near term? I define the 'near term' as a couple of years. Mikkelson posted a question about the potential benefits of adding serpentine to one of his troughs, and it struck me that I had no idea what, if any, effect, a particular kind of mineral/rock would have on the soil over a few years. I know that grinding up limestone or using limestone or tufa dust in a particular soil mix will effect the PH, but will just regular rock?
