It’s a Small, Small World

I just finished reading The Soil Will Save Us by Kristin Ohlsen.  I highly recommend this book.  Don’t be put off by the schlocky title; it is a well-researched and incisive report on the state of knowledge about soil.  It shows that much of the carbon now in the atmosphere could be locked up in healthy soil.  However, it is the nature of healthy soil that was most enlightening for me.  There has been growing awareness for some years now that healthy soil contains a remarkable variety of flora, fauna, and fungi providing essential nutrients to above ground-plants: just a teaspoonful of soil can contain 40 million individual bacteria cells.  

Bacteria are the most important life form on the planet. We live in a virtual sea of bacteria and less than one percent of them have been isolated and studied. They are opportunistic and don’t pass up a new niche; i.e. hydrothermic eubacteria, that had previously been found living only by deep sea hydrothermic vents, have been found colonizing prosthetic hip joints!  They are a potent force to be reckoned with.  Whether we’re talking soil or our guts, it is best to not disturb a vibrant and diversified population of bacteria that we can work with.  They make up 90% of the cells in our bodies.  This should give you a serious identity problem, as what you formerly called yourself is more like “yourselves.”   The genomes of your bacteria frequently interact with your human genome.  This interaction, known as the interactome, has proven to be a successful survival strategy for our human organism/partnership.

What I didn’t clearly understand is how integral those soil bacteria are to the healthy growth and function of the plants that grow in them.  My quantum leap in understanding was that if you think of an animal as an independent organism as discussed above, you can think of the soil and plants combined in the same way. You could think of the microbial world of soil as serving the same purpose for above-ground plants as the microbial world inside our intestines does for us.   Without those bacteria, we would simply starve.  When our plants appear to be starved, it may not be that the nutrients they need are missing, but that the bacteria needed to transform those nutrients into a form plants can absorb are not present.  That marks the importance of soil health.

This understanding needs to inform the way that we treat soil.  If we add artificial chemical fertilizer to soil, the above-ground plant will not secrete sugars to feed the soil biota.  Those bacteria will, to some extent, starve.  Without those bacteria, the plant becomes totally dependent on the chemical additives much the way we are when we are on an IV tube. Bypassing the intestines will starve out our bacteria.  Fortunately, for both us and the soil, these bacteria are extremely robust and can repopulate quickly.  We just can’t be sure that the new bacteria will have our best interests at heart.  The best defense is to maintain a steady population of bacteria that work for you and that will help to control or eliminate unwanted bacteria.  The lesson here is don’t disrupt the symbiosis of soil bacteria and plants:  don’t add “IV tube” artificial fertilizers. That is not to say that nothing need be added.  Northwest soil is generally too acidic for food plants and some minerals are lacking.  Soil can be amended without stressing the bacteria culture.

Even worse, if we use pesticides or herbicides, biodegradeable or not, we will kill the “soil,” and it will no longer provide nutrients until it is recolonized (or we add artificial fertilizer: the vicious cycle).  Besides adding organic matter, the real value of compost is its bacteria. We are aware of less than 1% of the bacteria that exist in any soil sample, and it may be that many of those bacteria provide a plant the ability to coexist with weeds and pests.  

If we dig up or turn over the soil, we need to understand that we are disrupting the soil ecosystem and its fragile tilth.  I’m reminded of my son’s recent accident, which required that his intestines be thoroughly inspected.  The worst after-effect of his accident and subsequent care was the indigestion that resulted from handling his intestines.  I’m coming to think that I want to leave the soil unturned and amending with mulch and cover crops only.  

Most of us know only too well that an untended garden does not take care of itself.  If we take plant material out of the garden, we need to put some back.  We need to account for mineral content and Ph balance.  If we plant a lot of one species in one place, there will be pests taking advantage of it.  If we don’t weed, our favored plants may be starved of light. When we expose ground by weeding, more weeds will quickly take their place.  I’m going to try to just mow the weeds with a clipper and not disturb their roots, which, dead or alive, will feed the bacteria.  Of course, we will need to water, but a healthy undisturbed soil will require less water.

Soil that has been abused by chemicals or that is unsuitable for the plants we want to grow will need to be amended, but the goal should be healthy soil without loading it with artificial nutrients or killing agents.  Refer to the Guides for Garden Products and Practices compiled by Michael Laurie and Diane Emerson, available at your local store.  Take care of your soil and it will take care of you.

Comments?  terry@vashonloop.com