Soil: Nature’s Intestines

There aren’t many things on this planet that could be considered half-living. Zombies perhaps, or the shrivelled shell of the once vibrant tomato plant that graces my balcony (I have since lost hope of a full resurrection). But soil – the trampled, paved, mentally discarded substance beneath our feet is a half-living being. It’s both alive and inert, the nexus between the biotic and abiotic worlds. Soil runs the engine room of biological reincarnation, turning one living being into the next.

10 years ago I made a terrible decision. I bought my daughter a dog. Like most puppies, Fluffy started out cute – furry little ears and face, tiny legs and paws, a cute little pink tongue. She would burp and yawn and fart while we watched with delight. Fluffy was adorable. Then she changed.

Something happens to small dogs, perhaps when the reality of their perpetual short-stature becomes evident. Dreams of ruling the dog park, running alongside the St Bernard and Alsatian are shattered. Then they snap, yip and snarl. If they will be small then they will be the noisiest, nippiest, snarliest small dog on the street.

For years Fluffy growled, launched herself at old ladies in nice hats, and nipped at my ankles when she was feeling particularly mean. To my daughter she was a goddess, ever deserving of sacrifices (my stockings) and gifts (fresh chicken breast from the butcher, sliced finely then hand fed to the creature).

Finally, one magical day, it ended. Fluffy pooped her last poop on the doorstep, farted her last fart on my roses, and exhaled the last of the CO2 from her lungs.

That CO2 might remain in the atmosphere for a decade, eventually inhaled by another organism. Her last little toot on the roses contributed carbon dioxide, and some nitrogen and hydrogen to stimulate their growth – I cannot begrudge her that.

I could finally bury the creature in the back yard (trying not to sound overly cheery while wiping away my daughter’s tears).

“Why?” my daughter asked, her big brown eyes imploring me to explain and fix the tragedy.

“Because all living creatures die,” I said, “Like Grandma.”

She nodded, but she was too young to remember grandma. In all honesty I think my mother-in-law frightened her – hairy chin, brown teeth, and skin that had long ago given up hope of remaining attached to her cheek bones.

“It’s normal, but it’s very sad,” I brushed her hair back from her forehead. “Perhaps we can plant some flowers for Fluffy,” I find some seeds for Fairy’s Petticoat Peony – a very Fluffy flower indeed.

Becoming Soil

Fluffy is about to contribute more to my garden than her previous gifts of excrement.

With the satisfying final thwack of the shovel on the fresh dirt mound, Fluffy begins her transformation. Soil microbes begin a feeding frenzy, converting Fluffy into the very soil in which she lies. The nitrogen from her muscles, the iron in her blood, the sodium in her beady, staring eyes, begin their conversion from dog to soil.

Corpses are a feast for soil microbes, containing far more essential nitrogen and phosphorus than any plants root exudates they’ll ever find. When a body falls in the woods and no-one hears it, soil microbes receive their version of cake – protein, sugar, carbohydrates.

Heterotroph bacteria get to work, breaking down the eyeballs and liver into their individual elemental components. Aerobic bacteria do this via respiration while anaerobic bacteria use fermentation. For a dog this is neither here nor there, but for a beer drinking human the thought is almost poetic – what once processed beer, now become beer for another.

Some bacteria breakdown proteins, releasing ammonia in the process. Others convert the ammonia to nitrite, then nitrate. Nitrate is the major form of nitrogen plants use, and Fluffy’s tongue is on its way back into the food chain.

Microbes colonise the corpse in search of carbon, their main food source. The noble earthworm helps out by incorporating organics into the soil, making it easier for microbes to do their work. All creatures of the underground play a part.

Imagine the soil ecosystem as a jungle. A microscopic, dense, complex being filled with wondrous creatures. The jungle is beautiful and unforgiving. There are vampires (vampyrellids), elephants (earthworms), and trees (fungi). The jungles we see above ground are deserts compared to those underground.

It may sound macabre but this process is completely natural.

Were it not for the voracious appetite of soil ecosystems, the world would be covered in layers of corpses. We must not abhor, but rather thank these tiny creatures.

All humans inherently know this process happens (yes – you do) and some even try to use it to their advantage – many a murderer has sought to use soil as a hiding place for their victims.

For reference, a peat bog is not a good place to dispose of a murder victim as the climate preserves rather than decomposes. The cold, anaerobic bogs of Denmark have yielded a few well preserved bodies, such as the 4th century ‘Tollund Man’, disturbed in 1950 by two brothers digging for peat. His skin had been preserved like leather by the tannins in the bogs.

The Tollund Man didn’t decay for the same reason peat bogs can exist; the climate is too cold and anaerobic for much microbial activity, allowing organic matter can build up over time. You’ll never find a peat bog in warm, wet or dry climates, as carbon cannot accumulate. A rainforest soil is like Delhi, a peat bog like Dunedin. One busy, churning, turning.  One quiet and slow. For this reason, rainforest soils are almost never black and humic though they dress themselves in lush, vibrant clothes to hide the poverty within.

It’s Elementary

In time, a few months perhaps, Fluffy has become soil, though her bones will remain for at least a decade.

She has become the elemental components that originally made her. For Fluffy, like you and I, is stardust, and we are all very old. About 13.8 billion years ago – give or take a few million years – the universe came into existence in a vast flash of mathematical convolution. Allow a few billion years of gravity, heat, pressure and explosions, and the cosmic cauldron threw out all the elements necessary to make life.

The universe had a few more tantrums, finally calming down enough for the Earth to cool, the crust to form, and in time, life to make its way out of the primordial ooze. Since then only one element essential for life – Nitrogen – has been manufactured by humans. The rest – the carbon in our bones and the iron in our blood – were formed nearly 14 billion years ago.

Living beings cycle through the soil, just as Fluffy is doing now.

Becoming Life

‘Ashes to ashes, dust to dust’ is less the work of God and more the work of soil microbes.

In time, Fluffy’s elemental components will make their way into the grass above, the nitrogen and iron pumping dark green hues into the blades that now grow twice as quickly. Even in death Fluffy makes life difficult, warranting two trips with the mower this week. I cut the grass, the blades fall, and biological reincarnation continues. Elegant, efficient, beautiful.

“Look Mum! They’re growing. Fluffy flowers!” my daughter jumps excitedly next to the pink peonies dutifully growing where they were planted. A particularly fluffy patch of dandelion weeds has taken root – how appropriate.

A pretty reminder of a sad or even abhorrent history is not uncommon. Nature takes over, covering our sins with her tendrils, rhizomes and petals. Sometimes she makes a beautiful reminder like the poppies of Flanders Field in Belgium. The fallen soldiers gave nitrogen, iron, oxygen and more to the ground, who took it, transformed it, and threw up thousands of blood red poppies in return.

Writing about the Battle of Landen (1693), British historian Lord Macaulay notes:

“The next summer the soil, fertilised by twenty thousand corpses, broke forth into millions of poppies. The traveler who, on the road from Saint Tron to Tirlemont, saw that vast sheet of rich scarlet spreading from Landen to Neerwinden, could hardly help fancying that the figurative prediction of the Hebrew prophet was literally accomplished, that the earth was disclosing her blood, and refusing to cover the slain.”

Tales persist here and there of English fertiliser factory employees in the early 1800s, scouring battlefields for bones of men and horses. Bones are rich in calcium and phosphorus, essential and expensive plant nutrients.

“…more than a million of bushels of human bones were imported last year from the continent of Europe into the port of Hull.” The Religious Miscellany, a text from 1823 describes.

“… a dead soldier is a most valuable article of commerce; and for aught known to the contrary, the good farmers of Yorkshire are, in a great measure, indebted to the bones of their children for their daily bread.”

Gruesome but honest. Death is necessary for life.

Biological Reincarnation

The circle of life is not just a song from a famous children’s movie, now theatre production. It is a reality. It happens because of the what lies underfoot.

Soil is the world in which reincarnation takes place, for reincarnation is a phenomenon, just not in the way Buddhists describe it.

Every living being, including you, is reincarnated…well, recycled. Your eyes contain atoms that were once, perhaps, a dinosaur’s toenail, your eyelashes maybe once a blade of grass.

That half-living, subterranean rainforest you scrape off your boots at the front door is what turns one living being into the next.

Enjoy the time, space and elements you rent on this planet. If you’re lucky, in about 80 years you’ll give them back for something or someone else to use. Perhaps you become a vase, or a piece of art, a tree or a flower. Maybe you float around the atmosphere for a few years, or drift across oceans, bumping into other particulate beings on your travels.

Everyone leaves a legacy, in something or someone else.

It is the soil that allows us to do so.

Alisa Bryce is a soil scientist and writer. She likes digging holes, looking at soil, playing with soil, writing about soil, admiring road cuttings, and browsing foreign supermarkets. In a past life she was a (friendly) piano teacher. CHECK OUT ALISA’S WEBSITE