When a seed sprouts, that event does not go unnoticed in nature.
As a first tiny root emerges and begins to poke its way into the soil, an outer mucus layer gives off chemical signals that announces its presence to surrounding organisms. These other organisms may have been lying dormant for months just waiting for such a root signal.
One way or another, most of these other living things see new roots as food. Some, such as nematodes, burrow into the roots and damage the plant. Others graze on roots directly. Still others, including many types of bacteria and fungi, have symbiotic mutually-beneficial relationships with roots. They are nourished by root exudates that are provided through the plant's unique ability to perform photosynthesis - to poke leaves up above the soil to gather solar energy.
The mycorrhizosphere, the zone that surrounds plant roots, is normally rich in life. It would be difficult to even begin to explain all the processes that go on in that bio-activity zone. The complex interactions between the plant and countless other soil organisms are still little understood.
For our purposes, however, let's just focus on what many soil scientists have identified as the keystone factor - Endo and Ecto-type mycorrhizal fungi. At the time a seed sprouts in a normal healthy soil there will also be many thousands of these fungi spores patiently waiting for a wake-up call from a new root. When the signal comes, the closest spores quickly come to life and attach to the root.
Time is then of the essence to both the plant and the friendly fungus. If the mycorrhizal fungi do not rapidly fill the mycorrhizosphere with protective sticky hyphae, the always-lurking root predators and pathogens will gain access. In a worst-case scenario, if there are no beneficial fungi spores in the soil, then new roots are dangerously unprotected. This happens in soils where the biological activity has been destroyed by chemicals, excessive tillage, or over-fertilization.
A root that lacks mycorrhizae is not only open to attack, but also cannot uptake nutrients efficiently. This is another evolved role that the fungi performs and some plants will literally starve without the fungi's presence, unless the grower loads the soil with abnormal amounts of fertilizer. (These are the plants that are incorrectly called "heavy feeders" by gardening authors. Rather, they should be called plants that have evolved fungi dependence.)
From the perspective of the fungi, which is nourished only by plant root exudates, if the plant dies, then the fungi won't live long enough to form new spores for next year. So any signal of stress by the plant triggers an instinctive response to a higher level of fungal activity. (We are learning to use this instinct by withholding water from seedlings for short periods of time - the fungal colonization is then greatly speeded up.)
Similarly, if the grower puts high-analysis "plant food" in the soil, especially fast-acting phosphorus, the plants may feel content and not give off the assistance signals that the fungi respond to. This seriously disrupts the natural underground process. With too much P, the fungi may not colonize the roots at all and while the plant may grow reasonably well with the synthetic fertilizer, it will be more prone to insect damage, pathogens, and diseases. The grower loses the "free" nourishment and protection that mycorrhizal fungi normally provide to plant roots.
For sterile potting soils or cropland soils that may not have good numbers of beneficial spores, we recommend treating seeds with our fungi inoculant. One of our products is micronized and clings nicely to slightly-damp seeds, or can be mixed into water and applied as a drench after seeding is completed.
Create and encourage these natural partnerships and see the difference in plant performance!
A side note, readers: We have developed a new product that features trace-element volcanic minerals, plus long-lasting biostimulants and fungi spores. This new MycoMinerals (TM) product is designed to be lightly scattered and tilled into gardens or depleted croplands, or blended into potting soils. In our grow tests, we have observed excellent plant response, but would now like to see how the product will perform in a variety of situations. If any of you are interested and able to set up comparative tests (such as half a garden area with and half without, or side-by-side plantings in pots, or a small section of a field, etc.), please let me know. I'd like to set up perhaps 50 such tests, especially in poorer soils. For the reasons noted above, the test will require withholding of synthetic fertilizers.
President, BioOrganics, Inc.