This is a blog post about how rocks turn into people.
Soil doesn't get the attention it deserves. We mostly take it for granted or curse it when it hitches a ride on our shoes into our houses. But soil is of course critical for our food supply, it's also the filter that creates clean rivers, soil is beneath any beautiful landscape, and soil is worthy of our admiration for being the most complex ecosystem on the planet. Indeed, soil is the antecedent for life on land as we know it.
The earth's crust is rock, rock full of the building blocks of life, but rock nonetheless. Soil is that thin gateway that transforms rock into things like lawns, bees, dogs, beautiful flowers, wooden chairs (trees) and of course humans. So how do elements from the earth's crust, aka rock, turn into a person?
It's the soil food web that ushers the humble phosphorus atom from a grain of silt up through the food chain and ultimately into a strand of your lovely DNA.
"But wait!" you say, "Where's the rock in this diagram, isn't this a blog about rocks turning into humans?"
You're right, this diagram is dramatically simplified. Aside from the omission of rock as the original source for all the mineral elements of life, we don't have arrowheads pointing back to plants from every single organism group to represent the plant-available nutrients they are excreting. OK pooping, this is the Soil Dynamics blog, we handle all the poop from both zoos in the area, so we might as well call it what it is. Even protozoa poop, in their small and humble way, but it definitely adds up.
You should mentally place rock along side "organic matter" in the diagram. Bacteria and fungi have been perfecting their rock-eating for 4 billion and 1.8 billion years respectively. They are so good at mining the necessary minerals from rock that nobody else in the food web has bothered to evolve mechanisms to cut out the middle-men. In other words, bacteria and fungi work tirelessly to turn rocks into their own organic bodies, and all the thanks they get is to become the potato chip of the soil world. Everybody eats them, from one-celled protozoa, to earthworms, to beetles. Even chickens will scratch around in soil and eat visible fungus... not to mention, well mushrooms are delicious. This process of nutrients flowing around in a food web is called nutrient cycling.
"OK, this is even worse, there's no pictures AND no rocks on this diagram!" you might be thinking. Sorry about that, but hang on! Top left see 'nutrients from mineral', mineral means rock there. When an atom of phosphorus or sulfur or molybdenum is so inextricably bound up in the mineral lattice of a grain of sand that all seems lost, you better believe that some needy bacteria or fungi has the tools to chew it out of there. When that bacteria or fungi is eaten by a nematode near the root of your tomato plant, most of the time that nematode has enough phosphorus, sulfur, or molybdenum. So that nutrient goes right through the nematode, out its back end in a plant-available form, so it can go into the tomato plant root. Then into you. Rock becomes human.
Well there you have it. Humans are made of rocks. And water. And air because bacteria are able to munch nitrogen gas from the atmosphere when they need more nitrogen to build proteins. By adding compost to soil, you are adding useful organic matter that our microbe allies can mine for nutrient and energy. Also, well made compost contains a thriving ecosystem of soil microbes and it doesn't harm existing beneficial microbes in the soil when used as an amendment.
But there is an alternative to a healthy soil food web and the choice is yours whether you have a lawn, 10,000 acres of rangeland or cornfield, or a houseplant. Chemical fertilizer is concentrated plant-available forms of nutrient, extracted by energy intensive processes from air or rock or petroleum. This shortcut to soil fertility produces immediate results when you're looking for a green lawn, but it also produces immediate and devastating results when you're looking for that abundant population of earthworms, fungi, amoebae etc.. Chemical fertilizer is salt-based, and our microscopic allies are very much like slugs. You do the math. Once the soil microbes are crippled, soil is addicted to regular inputs of soluble fertilizer. Plants living in a thriving soil ecosystem get balanced constant nutrition, so they are less susceptible to pest and disease. Pests and disease attack and damage chemically fertilized plants more dramatically, so pesticides are the quick fix... Addiction mode.
On a subject as complex as soil ecology, there is always more to say. I hope this post has been interesting. Many soils are damaged, and many of our readers would like to reestablish a thriving soil ecosystem in their lawn or garden. That said, fertilizers of all stripes can be used more or less responsibly, make sure to always follow application rates. The worst of the results that powerful chemicals are capable of can be avoided by following directions!. As we publish more blogs, we'll have to link them here. I'd say we owe a "how to manage a thick lawn without inorganic fertilizer and herbicide" post. But in the mean time, feel free to comment here or on our facebook page, share your best tips for landscaping and gardening.