I also probably shouldn't re-interpret the Beyfuss argument too much either, but its available directly from him in another thread, and I had a brief chance to discuss with him this weekend. I hope he'll correct me if I misspeak... Your paraphrase is the main argument he now makes (i.e. gypsum can improve a good site, but not make a bad spot a good spot). I'll defer to his knowledge on that part, and assume he's right. The part I disagree with is that microrhyzal communities are slow to develop and that without them, calcium additions are of limited use. To that I would cite 3 or 4 peer review studies where adding calcium and/or lime to really poor sites did in fact improve ginseng growth. The fact that calcium improved plant growth is indisputable (we're talking on the order of doubling root mass), so the only question to me is whether they improve the site enough to make it worth growing ginseng for profit. I asked Dr. Beyfuss about that this week, and his opinion is basically that it improves growth, but not enough to make it worthwhile. Hopefully, WhitJr will be able to tell us whether that was true for him in a few years. In at least one of the calcium addition studies conducted on poor sites, calcium improved growth dramatically, but plants still died in a few years.