From my e-friend Rocky, a handout on soil biology that summarizes much of the great book Teaming with Microbes, which shows you exactly what's going on in good garden soil and how to "feed" the good guys in there:


The difference between rich, fertile soil and poor, infertile soil is essentially this:  the mineral composition of the soil.  The flavor and nutrition in fruit, grains, and vegetables are based on the soil minerals available, not the amount or type of organic matter. If a needed mineral is missing, it is just that, missing, and no amount of organic matter will make up for it.  No amount or combination of the air elements Carbon, Oxygen, and Hydrogen will add Zinc to your soil, and all plants and animals need Zinc. Plants also need Copper and Iron and Manganese, Calcium and Magnesium and Phosphorus, and at least seven other essential minerals (animals need at least fourteen more), and they need them in an available and balanced form.   Rotting organic matter may release growth stimulants like Nitrogen and Potassium, but the other minerals are what create sweetness and flavor and nutrition in food.  Without these other minerals you may achieve high production, but you will not achieve the highest quality.

We are Organic, Biodynamic, Biologique, and Sustainable gardeners, and we strongly support the idea of a living, energetic, biologically active soil. We have learned that the absolute best cannot be achieved without a full complement of minerals available and in balance.

BSOs Beneficial Soil Organisms

The focus is on the mineral nutrients needed by plants, animals, and people to ensure outstanding nutrition and vibrant health.  Why do I also recommend and use beneficial soil fungi and bacteria?

For the same reason that bakers use bread yeast, champagne makers ferment grapes with champagne yeast, brewers add beer yeast, yogurt is made with yogurt starter, and cheese makers use the culture that will give them the kind of cheese they wish to make.  One can wait around and hope that the right yeast spore will fall into the vat and create champagne, or one can increase the odds in their favor by adding the cultures that they want right at the start.  It is wise to be sure that the best possible soil life "culture" is there and ready to make the minerals and organic nutrients in the soil available.

BSOs are valuable for freeing nutrients that are in the soil but "tied up".  For example, many soils have great phosphate reserves, yet the plants growing on those soils are starving for phosphate.  Many farmers and gardeners in this situation resort to adding soluble phosphate fertilizers, in either organic or chemical forms, to a soil that already has plenty of phosphate, only to have the added phosphate tied up and unavailable to plants within a few weeks.  The reason for this is that the mineral Phosphorus is an extremely active "acid" mineral.  It has a powerful negative - charge, and just can't wait to latch onto the nearest + charge.  The nearest + charge is usually Calcium, and together Ca and P form Calcium phosphate, a very stable compound and exactly what bones are made of.  Seen any water-soluble bones lately?  No, it takes either strong acids or the right microorganisms to break the Ca-P bond. 

The USA and other countries have adopted rules for fertilizer labeling that say only water soluble
forms of N, P, and K may be listed as fertilizer "claims".  Two of the important soil amendments that we recommend and constantly use ourselves are natural phosphate ores: colloidal clay phosphate from Florida and Montana rock phosphate.  If one looks at the label on a bag of either of these well-known organic-approved phosphate sources, one will read that they are only rated to contain 3% phosphate (P 2 O 5 ),  0-3-0 is what the bag says, meaning 0% N (Nitrogen), 3% P (phosphate), and 0% K (potash).  Yet if one reads the fine print on the label, they learn that the total phosphate content is closer to 30%.  So why are these rock phosphates only rated 3% when they contain at least 20% total phophate?  Because only 3% of the total weight of the amendment is water-soluble phosphate; the remaining 18-28% is "married" to Calcium, that Calcium-phosphate bond again, and not water soluble. Certain strains of bacteria and fungi are able to to break the Ca-P bond and make the phosphate (and the Calcium)  available again to the other soil life and to plants. As a biological process, it proceeds slowly and steadily, providing long-term mineral security.

Another good reason to use pro-biotic soil cultures is that many soils have a hard time breaking down organic matter to form humus, the process of making the minerals and other nutrients in the organic matter available again to the soil life and crops. Seeding the soil or the compost pile with the right biology will greatly assist in breaking down tough plant roots, wood chips, corn stalks, and other "chunks" of organic matter in the soil, releasing the tied-up nutrients all along the way.

Here is a third important reason to use a good BSO culture to seed the soil:  Healthy soils always contain healthy symbiotic fungi.  95% of plant species have a natural and ancient alliance with the soil fungi.  Some fungi send out their long "roots" called hyphae
( hi -fee) for many meters, both deep into the soil and just below the surface in the topsoil.  They search out nutrients and moisture and bring them back to share with the plants.  Other fungi are smaller, and only live close to the plants they are partners with.  They break down small rock particles while searching for nutrients, digest dead organic matter, and even protect the plants from disease by producing antibiotics; the originals for all of our antibiotics were from the fungi.  (Penicillin is produced by the common blue bread mold.)  In exchange for being fed, helped, and defended, the plants feed the fungi, sharing the sugars and other carbohydrates that they make in the open air and sunshine with the fungi that never see the sun. 

The name for these types of symbiotic fungi is mycorrhizae (my-ko- riz
-ee) , or mycorrhizal (my-ko- riz -al) fungi.  Myco means fungus and rhizae comes from rhizome and means roots.  Fungus root is what they're named and what they are.

Some mycorrhizae (my-ko- riz
-ee) actually intergrow with the tiny root hairs of the plants.  The plant's roots are a combination of fungus and root tissue; the fungi share their own sap with the plants that are their partners; this type is called endo-mycorrhizae because it lives partly within (endo=inside) the plants that are its symbiotes.  90% of cultivated plants partner with endo-mycorrhizae.  Other mycorrhizae grow right next to the plant roots, sharing nutrients with the plants through the soil water/nutrient solution.  Ecto- means outside; ecto-mycorrhizzae live entirely outside the plant roots. Most trees and shrubs partner with ecto-mycorrhizae. A good tip if you are planting new or having trouble with old shrubs and trees, either ornamentals or fruiting types, is to find a place where the same plant is healthy and growing well and scrape off a little of the topsoil or surface duff to "seed" the soil around your new or problem plants with the BSOs from where the same plants are thriving.  Plants can usually live without their fungal and bacterial partners, but they won't thrive the same way they do when they have all the help they can get.

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