Who Knew? Recent Discoveries inside the Soil Food Web

Sometime in the late 90’s, I asked 450 members of the Garden Writers Association if they knew what a ‘mycorrhizal’ was or had ever heard of plant exudates. No one raised their hands.

All were amazed to learn that 96% of plants have a symbiotic relationship with fungi (mycorrhizal) called a mycorrhizae. And the notion that most of the energy produced by photosynthesis was actually used by plants to produce sugars and proteins that dripped out of root tips (‘exudates’) in order to attract specific bacteria and fungi to the rhizosphere was a total revelation.

You can imagine what happened when it was explained that plants can subsist off of two different kinds of nitrogen (ammonium or nitrates) and that some plants prefer one over the other!

Most flowering perennials and conifers, as well as most tree fruits, ornamental trees and shrubs do far better in soils dominated by fungi. Lawn grasses, vegetable row crops and flowering annuals, on the other hand, grow best in soils where the bacteria dominates.

The implication of these facts to garden practices was clear. Rototilling, using chemical fertilizers, applying herbicides, pesticides, nemacides, fungicides and all the other ‘icides’ were practices that hurt the natural order. Why were we using these things? Who fertilizes and ‘icides’ the Redwoods and how did they get to be 380 feet tall and live 500 years without Miracle-Gro?

Ten years ago you could forgive those of us that were “Better Living through Chemistry Gardeners” and even those of us brought up reading Organic Farming and Gardening for not knowing this stuff. When you mentioned ‘fungi,’ ‘bacteria,’ protozoa’ or ‘nematodes’ garden writers would think ‘bad guys.’

It’s only been since the advent of electron microscopes in the past few decades that scientists have been able to actually study the microscopic workings of our soil. Who knew that a good tablespoon of garden soil could contain half a billion to a trillion bacteria or, are you ready for this: twelve to fourteen feet of invisible-to-the-eye fungal strands known as hyphae.

Who knew that plants attracted bacteria and fungi to their roots so that protozoa and nematodes would eat these single celled organisms, poop out the excess nitrogen right in the rhizosphere in plant useable form and those feed the plant? Wow! Ten years ago this was really news.

Ah, but lots of advances have occurred in 10 years. We now know how things work (and I have written a Wonderful Book on the subject called “Teaming with Microbes: A Gardener’s Guide to The Soil Food Web–check it out on Amazon).

Today, in 2007, there is no excuse for any garden writer to advise practices in the garden that negatively impacts the soil food web, the complicated but elegant linking of food chains, from the single celled organisms all the way “up” to man.

Rototilling, for example, breaks up the subway network of fungal hyphae, but also create soil structure, hold most of the soil’s carbon and provide air and water passageway when they die off. High salt chemical fertilizers kill fungi and bacteria at the base of the soil food web and impact larger members as well.

What all of this new science means is we have to make an adjustment to the way most of us, even those who are already organic, practice our favorite sport. We have to take into account the real science of the soil. It sounds daunting. It sounds impossible. It sounds like it isn’t going to be fun.

Trust me, however, when I say it is not only fascinating, but once you make the switch over to gardening with the Soil Food Web as opposed to gardening with Chemistry and Myth, you will find that gardening not only becomes easier (fewer lawn mowings, no rototilling, no high nitrogen induced weeds and so much more–or less), but it also becomes safer as you can well imagine. (Just google the words “dogs,” “lawns” and “cancer” together and see what you get).

We are in a new age. You are reading this on the internet. Your life has been radically changed–most for the better, since you started using a computer. The way you garden should radically change, too, once you embrace the science that is only so recently available to us. Soil Food Web advances have a great deal of application to taking care of our yards and gardens.

Guest Author Jeff Lowenfels