CRITTERS, again ...

By Judy Swain

I wrote previously in this column of how the enticement of making sauerkraut out of squash led me to turn cook books on their heads. All thanks to largely unsung heroes, bacteria.

Bacteria are residents on the surfaces of living plants and humans have made miraculous use of them for THOUSANDS of years for food preservation through ‘fermentation’. Although we call the vegetable ferments ‘pickle’ and ‘chutney’ they are really “vegetable yogurt”, since they give us the same benefits we look for in yogurt, [Do we thank them? pay them?]

Exciting … even weird… enough. But recently I had my eyes blown wide open to yet another MAJOR role these unseen critters of our planet play. I was introduced to this story by, of all unlikely sources, our local watershed authority.

Their interest comes from concern over the condition of our waterways as they fill up with the run-off from our agricultural lands. Soil particles, minerals, and agricultural chemicals are being borne off by wind, rainfall and melting snow. The Seine, Rat, and Rosa Watershed Authority recently hosted a farmer from North Dakota. A farmer to talk to farmers. From his experience and experimentation.

During Gabe Brown’s talk we were shown the different response of soils to water in a particularly vivid test tube demo. We saw some soils retain their integrity when water was dumped on them, while others simply disintegrate. We were told the key to the different responses lies in the population of microbes in the soil.

When present in sufficient quantity, microscopic, underground critters secrete biotic glues that coat soil particles and hold them together in clumps. Aggregated soil has been described as looking ‘like chocolate cake’ … an image we can all relate to! This soil will hold together, in wind and in rain. It is porous, like sponge. The pores are lined with the same biotic glues. Rain infiltrates the soil through these pores, is absorbed and held there. How much moisture the soil can hold, and how quickly it can absorb it, is termed ‘effective rainfall’.

If the soil is non-aggregated it can absorb miniscule amounts of effective rainfall. When Gabe first measured the effective rainfall on his farm it took one hour to absorb ½ in of water.

If the soil is well aggregated, and contains high amounts of vegetative matter, it will absorb much more. Today his effective rainfall is 1 inch in 9 seconds, and 2 inches in 16 more seconds. An astounding change but Gabe says that the formation of this kind of absorbent topsoil can be “breathtakingly” rapid.

So drought conditions can be self-inflicted, since aggregation of our soil is directly affected by our farming practices.

Micorrhizal fungi are other major players; other microscopic underground ‘livestock’. They are composed of long thin filaments that act as extensions of plant roots going far into the soil. Here is the amazing part : plants and mychorrizae have two-way radio systems to communicate their needs. Plants pull carbon from the CO₂ in the air and turn it into sugars. That is photosynthesis. We learned that in grade school. What we did not learn then and are learning now is that plants share this ‘liquid carbon’ by actively secreting it out through their roots to feed fungi and other life forms. In exchange the mycorrhizae bring minerals, complex amino acids and other complex molecules. The vast majority of soils are NOT deficient in minerals. What is lacking is the microbial life to bring the minerals to the plants.

Apparently when we till our fields we seriously disrupt underground life, particularly the mycorrhizae. Their long filamentous highways are simply destroyed.

Furthermore, tillage infuses oxygen into the soil, which stimulates opportunistic bacteria who then consume the carbon-based biotic glues that hold the soil, and pores, in place. Pores collapse, moisture is lost, anaerobic conditions develop, which further alters the nature of the microbes in the soil, even favouring denitrifying bacteria. Who ever heard of them before ?

But, can we really grow our crops without tillage? Can we actually depend on invisible life forms to do our work for us? Really?

Stay tuned for more counter-intuitive insights …