In a post the other week, I mused about where soil fertility comes from. In fact, what I was really wondering was, “where does the soil itself come from?” I suppose I knew the basics, but I’ve gotten a firmer grasp on it, and it’s pretty amazing. The very short version—physical processes like wind and water and glaciation grind or wear down base rock into sands and silts, and then when living things take root there, they put roots down. These roots harbor and foster myriad soil life, from bacteria and fungi to nematodes and earthworms. This soil life actually extracts minerals from the tiny particles of rock. Then a symbiosis begins, where the plants provide the soil life with sugars exuded from their roots, formed by photosynthesis, and the soil life in turn provides the plants with minerals and nitrogen. Then, when the plants (and the soil life, for that matter) die, still more bacteria and fungi decompose the remains and recycle the carbon and nutrients right back into the soil. The more green things that are growing on top, the more soil-building is happening below. Over time, such a system just gets richer, and more fertile, unless outside forces break the cycle. A beautiful film on the subject, “Symphony of Soil”; is available on Vimeo. Here’s the trailer—
The film costs a few dollars to rent, but it’s well worth it.
If you want to see a great example of how this soil creation works in real life, check out another film, “An Oasis in the American Desert”, where Geoff Lawton visits a swale system installed in the middle of the Arizona desert in the 1930s as part of one of the New Deal programs. It’s nearly unbelievable. It’s not in this shorter clip, but in the full version he digs down with his hands and pulls up soil that appears to rival what you could find in Iowa. AND—other than building the large swale that has captured water runoff, humans didn’t do anything at all to create this soil; nature created it without any human intervention, in eighty years, out of desert gravel and sand.
Now, the more one understands where soil comes from, and how it underpins nearly all life on earth, and certainly the existence of humankind, the more destructive, or even suicidal, our current agricultural methods appear. We are used to thinking of industries like mining and fishing as “extractive”, but a great many agriculture techniques are just as extractive. We grow many crops at the expense of the soil, and we use that soil up. Nearly all Industrial agriculture fall into this category, but so do the subsistence farming methods of many of the world’s poor.
As an example, take a typical industrial cornfield in the US. Everything that happens here is a disaster for the soil. The field is usually first sprayed with glyphosate in the spring, (“Roundup” or the like) which kills every living plant on it (here in Vermont, I’ve seen them spray as many as three times in the spring, before the soil is finally warm enough to plant corn). All those soil organisms, if not killed outright by the glyphosate, start to die when the plants above them quit growing, and quit exuding sugars. Then comes the plowing. The soil structure is pulverized, and the fungi hyphae that move minerals and sugars through the soil are physically cut and disrupted. The plowing also introduces large amounts of oxygen into the soil, and the soil carbon begans to “burn up” into CO2, which is released into the air. No plants are present to replace the carbon in the system, so the carbon content of the soil drops. As it drops, the soil can’t hold and retain as much water. At this point, thoroughly disrupted and devoid of plant life, the soil is wide open for erosion, from wind and water.
Because soils with reduced carbon content can absorb and hold dramatically less water (the carbon, or humus, acts like a sponge), the water runs off far more readily, and takes soil with it. Then, also because the soils hold less water, they dry faster, and once dry the wind takes yet more soil away.
Eventually the field is planted, usually with GMO seeds that allow yet more applications of glyphosate (just as a clarification, I don’t necessarily hold that GMO plants, by themselves, are horrible things. But in the case of GMO plants that resist glyphosate, they enable a form of farming that is quite destructive). The soil, lacking much of the life that gave it its original fertility, now needs to be dosed with fertilizers, which are nearly always derived from petrochemicals, as are the pesticides that are also applied. So, throughout the season, the soil endures the likes of anhydrous ammonia and Atrazine. The chemicals make it nearly impossible for soil biology to thrive, and the once-living soil begins to revert to “dirt”. Then, once the corn is harvested, the fields are bare yet again, and will stay that way until the next season.
Once land has been through this cycle a few times, its fertility begins to drop, and the crops become naturally weaker. At this point a truly vicious cycle ensues, with the crops needing ever more fertilizer and chemical supports, which is more and more destructive to the remaining soil biology. Over time, more and more carbon is lost, which contributes to global warming, and makes the soils ever more erodable. As the soils become more erodible, not only does more soil end up choking rivers and streams, but more chemicals go with it, and aquatic life suffers as well. In the US, the entire process is a disaster, from the soil in a Midwest cornfield, all the way to the dead zone in the Gulf of Mexico caused by the runoff of chemicals and fertilizer. And as the soil disappears, inch by inch by inch, the future of humans on the planet gets puts into greater and greater jeopardy.
So, what to do? We do have some options, and as you can tell from the title, they have something to do with permaculture. I’ll discuss those next time, in “Part Two”.