Older soils differ from younger soils because they have had longer to develop. As soil ages, it starts to look different from its parent material. That is because soil is dynamic. Its components—minerals, water, air, organic matter, and organisms—constantly change. Components are added and lost. Some move from place to place within the soil. And some components are totally changed, or transformed.

When aged soil starts to look dark, rich, and beautifully earthy, the soil is a living ecosystem, increasing crop yields and nutritional profiles, purifying and storing water, anchoring and stabilizing soils, protecting the land, and so much more. 

In this fertile environment, earthworms are able to continue improving the soil structure by eating the decaying plant material, mixing their nutrient-rich castings into the soil, and creating multiple tunnels for oxygen, water, and plant root growth.

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"If you spend any amount of time in the garden, you should already be quite familiar with your garden worms. These leaf-lovers are considered a gardener's best friend, and for good reason too. 

"Aristotle once called earthworms the intestines of the soil. Not only because of their uncanny resemblance to the human gut, but also because of their talent for digesting. 

"Worms kickstart the process of decomposition by making life easier for microbes. They take surface organic matter, such as dead leaves and grass clippings, and grind them up into small chunks using a specialized intestinal organ called a gizzard. 

"These plant residues are taken down and mixed up with the soil in a process called bioturbation. Earthworms work relentlessly, plowing tunnels through the soil. These channels act as pipelines for water and air to pass through, providing plants and other microbes with essential resources. 

"Inside the gut of an earthworm are millions of bacteria, which after the earthworm has shredded up all of the organic matter, go to work extracting the nutrients. This is called a mutualistic digestive system, because both the earthworm and the bacteria benefit. The leftovers are excreted and these are called worm castings, which are highly fertile and rich in nutrients, just what plants love. 

"It's clear that earthworms play a vital role in soil fertility, but an overwhelming number of studies show significant decrease in worm numbers, following repeated pesticide application. The good news is that you can encourage them back into your soil by adding more organic matter and mulched materials. 

"In just one square foot of soil, there may be up to two hundred worms, working hard to produce rich, fertile soil. That's two hundred experienced micro farmers producing top-quality plant fertilizers.

"So by looking after them, you're helping to ensure the best health for your soil."

| CLICK to learn about earthworms (2:57min) - also linked above