With few exceptions, farmers and gardeners alike complain when they have to deal with heavy clay soil - the type that sticks to their boots and tools. Whole industries exist to loosen such soil or to assist water in penetrating brick-solid surfaces.
But, if those frustrated growers were to step over to any nearby naturally wooded area, they would discover that the soil under those untended trees, shrubs and grasses is generally loose to the point where a person can scoop into it with bare hands.
What's going on here? Why dense sticky clay a few feet away from loose soil? Were the wooded areas just lucky enough to get better dirt?
Well, as usual, the answer is mycorrhizal fungi. Undisturbed, these beneficial organisms will completely colonize every square inch of the soil surrounding their host plants and form massive networks of interlinked hyphae (their microscopic root threads).
This hyphae network, sometimes called a "foodweb", serves many useful purposes underground: searching soil for nutrients that are brought back to the plant as needed; exchanging nutrients between established plants and seedlings; providing fodder for countless other soil organisms; preventing access to plant roots by pathogens; etc.
Indeed, it would be difficult to point to just one of these functions as being the most valuable to plants, but physically improving soils would have to rank near the top. The tiny platelets that make up clay are separated and pushed apart by exploring hyphae. This action "opens up" dense soil, which then gives water and oxygen easy access to the root zone - in effect, allowing the soil to "breathe" and quickly drain away excessive moisture.
Plants and all sorts of aerobic soil organisms thrive in such conditions, and their success then supports further growth of the beneficial fungi - a most useful and self-sustaining symbiotic cycle. When these fungi and their extensive hyphae network are destroyed by tillage and the application of high-analysis synthetic fertilizers, the clay platelets stack tightly together and the soil becomes compacted and waterlogged.
Many aerobic organisms, from worms down to friendly bacteria, cannot tolerate tight soggy soil, leaving growers on their own to deal with the stuck-together clay platelets. Tillage fluffs up such soil only temporarily, as any owner of a rototiller who then uses chemical fertilizers will verify.
The trend toward no-till agriculture makes very good sense from the standpoint of preserving and encouraging the underground community of microbial organisms (along with earthworms). Also, compost or shredded crop residues should be scratched lightly into the soil surface and only "gentle" lower-analysis, timed-release fertilizers should be applied.
Step lightly - there are valuable little critters under your foot!
Cheers, my friends,
Don Chapman
President, BioOrganics, Inc.