Ask Mariah: Living Soil
Wednesday, November 26, 2025
Dear Mariah,
I’ve heard soil being referred to as ‘living’. How can soil be ‘alive’… It’s just dirt… right?
Sincerely,
The Soil Skeptic
Dear Soil Skeptic,
I love this question!
Dirt is the ick on your shoes after a walk on a muddy path. It’s the muck that gets kicked up on the side of a pickup or ATV while driving through puddles. It’s the dusty tractor tire tracks left behind as a farmer leaves their fields. Even when dirt is in places you wish it weren’t, it still contains the mineral particles— sand, silt, and clay – all useful, but not living.
Soil contains dirt- but it has so much more!
Living organisms are what make the soil ‘living’. Healthy soil is an entire ecosystem– and just like any other ecosystem, it has living and non-living components!
Did you know that in just 1/4 teaspoon of soil, there are about 10 billion organisms? That’s more life than there are people on Earth!
These are just a few of the amazing creatures that make soil ‘alive’:
Earthworm activity adds air to soil, enhancing water absorption and providing oxygen for plant roots. As they digest plant material, they break it down and release nutrients that plants can easily use.
Bacteria like Streptomyces griseus break down complex organic matter. They also promote plant growth by producing hormones that stimulate growth. These microorganisms even create natural antibiotics that suppress diseases in the soil.
Image by S. Amano, S. Miyadoh, and T. Shomura
Fungi, such as Mycorrhiza, have a mutually beneficial relationship with plants. Think of them as an extension of root systems, reaching out and gathering extra water and nutrients for plants. In return, the plant provides carbohydrates produced through photosynthesis that the fungi cannot provide for themselves.
Image by Wilhelm Zimmerling CC BY-SA 4.0
Helpful Insects and Other Critters 🐞
Not all bugs are pests. Insects and other critters often get a bad reputation, but they can play a crucial role in healthy soil. Often, beneficial bugs help keep pest populations in check- ladybugs eat plant-damaging insects, ground beetles feed on grubs and weed seeds, and some nematodes and spiders help control harmful larvae in the soil.
These ‘good bugs’ can act as a natural pest control!
The Value of Living Soil
In short, healthy soil is a natural recycling system. All these organisms work together in harmony to convert plant material into organic matter, build soil structure, and help the ground hold more air and water. Better structure means less runoff, less compaction, and stronger, healthier plants.
And here’s the best part: when farmers or gardeners build healthy soil, they get all these helpful “biologicals” for free.
So what does healthy soil have to do with clean water?
Here is how it all connects:
When soil is living, it acts as a stable sponge. That sponge does three big things:
- Absorbs more rain, reducing runoff that can carry fertilizers and sediment into our waterways.
- Filters water naturally as it penetrates. The soil can trap pollutants and break them down with the help of microbes.
- Allows water to infiltrate slowly, rather than running off, recharging groundwater and keeping our watershed healthy.
Healthy, living soil has the power to protect our watershed.
Click here to read more about unsung soil heroes and stay tuned for practices that tap into the power of living soil. And if you have a question about soil, farming, and how it all affects our watershed- Ask Mariah!
Thanks for asking,
Mariah
