Q: What is the best way to purify soil to remove any diseases from it. Would adding bleach work?

A: Sterilizing soil is impossible in a practical sense. Even if you removed disease organisms from the soil it would quickly become contaminated again. It’s easier to concentrate on keeping plants strong so they don’t fall prey to disease. Giving a plant the appropriate amount of sun, water, fertilizer and drainage gives it most of the resources it needs to fend off, or easily recover from, pests. In my experience, making sure your clay soil drains properly, accomplished by the addition of organic matter, is the best way the keep plants healthy.