I have amended my soil (which is silty sand) with several carbon amendments for years, and been rewarded with abundant fungal rhizomes. It’s a pleasure to dig up a patch of bulbs to divide, and even as they go dormant, see roots tangled with fungal filaments. Interesting new book came my way this week: The Hidden Half of Nature, by David Montgomery and Anne Bikle, comparing thriving soils to thriving digestive tracts. Nice read, many references, worth pondering. As for sterile soils, a friend that compounds biochar plus mineral soil mixes for vegetable growing found that pot farmers were using his mix to grow marijuana plants, having started with sterile hydroponic conditions, and with microbially active potting mixes, could forego the clean room approach, and have sturdier plants that flower earlier and more. He was a little dismayed to see them buying out his bagged soil, not the market he was aiming for. Kathleen