Soil: the incredible story of what keeps the earth, and us, healthy, by Matthew Evans (ABC Books, 2021), is a wonderful book that was hard to put down. In the first of two Blogworthy posts we include short extracts that will give readers an idea of just how important soil is. The ground that we walk on is teeming with life, but then we decide to move more quickly so we ride over it on paved cycleways, drive over it on sealed bitumen roads. It’s more than dirt, it’s soil. When we visit the plant communities living at Munibung Hill we are a beneficiary of the work they are quietly doing everyday just as they have done for years. Making their own food, providing food and shelter for other species and generally going about their business without drawing attention to themselves or taking selfies as we have come to do. Without any fancy gadgetry the soil, the trees and the plants are producing the basic elements for life that sustain us day to day. Time to be grateful for soil and Munibung Hill. Here is the first of the two parts …
Plants do something that no animal can do: they make their own food. How can something solid grow out of seemingly nothing?
What photosynthesis does is nothing short of wondrous. When a plant takes in carbon dioxide and releases oxygen, the carbon remains in the plant. The carbon that the plant doesn’t exhale (the proper term is respire) is stored in the structure of the plant itself.
(Page 7 – In chapter 1. What You Eat is Made Out of Thin Air (and a Tiny Bit of Dirt) )
Consider carbon as the basis for practically all life on Earth. It’s like the original building block for everything from the smallest bacteria to the largest mammal.
In addition to carbon, the other crucial ingredient is sugar. And where does it come from? Again, photosynthesis. It is so extraordinary that we take it for granted.
Using sunlight as its energy source, a plant converts water and carbon dioxide into carbohydrate – sugar. Plants make sugar out of thin air. They make their own food! How insane is that? You can’t do it. I can’t. We humans can stand in the sun as long as we like, and all we get is a melanoma and hungry.
A plant can make sugars on which pretty much all other life on Earth depends.
Not only that, those plants that are making our food are also making oxygen for us to breathe, as a by-product of the process! (Page 8)
The science is amazing. Writes Evans: To my mind, the making of sugar out of thin air (and water) is sheer alchemy. A miracle. Without these sugars, no animal on Earth could exist – only other things that can photosynthesise, and a handful of specialized bacteria that can feed off Sulphur, methane or the heat from lava.
Without sugar there’d be no fungi. We’d not have most species of bacteria. There’d be no elk, no orangutan, no platypus, no koala. No animal life as we know it.
Plants provide the most important elements of all – energy in digestible form. (page 9)
Plants also take up another gas from the air – nitrogen – which allows for the production of protein. (Page10)
It’s been noted that invertebrates are an under studied, unappreciated group of animals, even though they make up the vast majority. The rest of us depend on them. The rest of us virtually ignore them, or classify them as pests because a small bunch of them in the insect group annoy us no end and so we would prefer that they were someplace else. We devote a lot of time and resources attempting to get rid of them, even though many are critical components of the web of life.
Says Matthew Evans in: Soil, “The only way to get the holy grail of soil textures, the ‘chocolate cake’ of soil, is through abundant subterranean life. As John Stika, author of A Soil Owner’s Handbook, says about soil life: “Without biology, soil is simply geology.”
About 3 per cent of soil mass is organic matter, which stands in for the cocoa and egg – in chocolate cake. The last two ingredients are water and air. About 25 per cent of the volume of living soil is air. A cake without air is a mudcake.
Planet Earth is really quit old, but our species, Homo sapiens, only branched off about 200-300,000 years ago. Compared to over 50 million human lifetimes at current life expectances since the Earth was formed, that only about 3,750 lives.
We’re relatively new arrivals on the planet and we emerged in an ecosystem that had been hammering along for a t least a good 3 billion years quite merrily without us. We are the result of all those species that came before us – including the microbes, which live in and on us.
Bacteria, archaea and fungi, not only make soil, they also make us. Viruses played a part in our development, with vestiges of their DNA in every mammal. We are less than half ourselves: 57 per cent of the cells in our bodies are microbes. It’s been estimated that there are 100 trillion individual bacterial cells in a single human body, which alters our genetic potential over a hundred fold. Our gut, in fact is one fothe most microbially dense ecosystems on Earth. (Page 25)
The more scientists have looked, the more they’ve realised that soil, like us, is driven by microbes. They’ve realised that the world is governed by things too small to see with the naked eye, and too numerous to count, except by using projections and algorithms. (Page 36-37 in chapter 4 Plants Don’t Eat Dirt: the Underground Economy)
Basic chemistry stripped soil of its status as diety, and endowed humankind with the ability to manipulate crops.
….what a keen gardener knows now, they also knew in the late 1800s – that compost is king, complexity seems to create resilience and that a well-grown vegetable tastes of the soil in which it was grown.
But it’s probably most important to remember that sold isn’t soil unless it comes in contact with plant roots. Soil with a scant few microbes, separated from plant roots by distance or time, is dirt. This is where subterranean life comes in.
I used to think that plants ate dirt. (Page 37)
Bacteria are part of what gives life to soil. The ‘germs’ we were taught to fear are discovered to be working night and day to gift us life. (Page 38)
In many ways fungi are the heavy lifters in soil. About 90 percent of plants and pretty much all trees, have relationships with fungi. We tend to think of fungi as decomposers, because we see mushrooms – the fruiting body of certain fungi – on dead trees. Many work in concert with plants, forming tight relationships with not only one plant but with many. (Page 41)
Research on soil fungi is increasing, and every revelation takes us further into the fantastical. Soil fungi can be used to clean up heavy metals. And there are other examples of how fungi return nutrient into the soil. (Page 44)
