Plants that feed the soil: Nitrogen fixers and mineral accumulators

Following up on June's discussion of the soil microbiome, we focus on two categories of plants: Those whose roots developed to harbor bacteria which fix nitrogen and those adept at pulling minerals out of the soil. How does these plants do it, how can we encourage and integrate them into our plantings, and what are the benefits to getting a yield and keeping all our plants healthy?

We'll also cover Permaculture Principle 8, Integrate Rather Than Segregate