By Laura Barnwell (Geologist, Soil Consultant, Lower Neshanic Community Farm)
We’re Part of a Living System
We’re all living inside one giant, interconnected biome — the land beneath us, the water around us, the air we breathe, and all the living things we cross paths with over a lifetime. And just as we’re part of the planet as a whole, we’re also part of our local ecosystems. As we move through our day, we’re giving something to that system and taking something from it, whether we notice it or not. Because of that, our choices ripple outward, and the health of the earth matters directly to our own well-being, especially when it comes to the food we rely on. Nutritious food only comes from ecosystems that are cared for — from the micro-organisms in soil all the way out to a watershed. When one part of that system breaks down, the rest eventually feels it.
Nature’s Essential Services
When we talk about soil health, it helps to start with the bigger picture: almost everything we rely on comes from nature’s “ecosystem services.” That’s just a fancy way of saying that we reap benefits from the natural world; things like clean water, materials for shelter, plastic to hold our chicken tenders, the minerals in your phone- even the planet’s ability to absorb our waste. And of course, one of the most important services is food. Every living thing in a food web depends on the level below it for nourishment.
Think about a simple chain: grass feeds the grasshopper, the grasshopper feeds the bird, and so on. Each level only thrives if the one beneath it is healthy, then passes this health onto the next level. Humans sit at the top of this chain, which means the quality of our food ultimately depends on what’s happening at the very bottom — the plants. And plants can only be as nutritious as the soil they grow in.
That’s why it matters that not all soils are the same. You can see this in your own yard: some spots grow lush plants, others stay bare, and some hold water after a rain. Forests, farms, and river valleys all support different vegetation because each landscape has different soil conditions and needs.
Dirt vs Soil
This brings us to a key distinction: dirt versus soil. Dirt is just broken-down rock — sand, silt, and clay. These particles contain minerals like calcium and magnesium, but they’re locked inside the particles, so how do we make them available to plants?
Soil, on the other hand, is definitely alive! It’s a mix of organic matter, decaying plant material, and a whole community of microorganisms working together. That living system is what creates the conditions plants need to grow strong and nutrient-dense. Right beneath our feet is an entire microscopic world—a living soil food web—that quietly supplies plants with the nutrients they need and, in turn, supports every other part of the food chain. Here’s what’s going on down there.
Sourcing Nutrients
Plants really only need two things from above the soil: sunlight and carbon dioxide. They take in carbon dioxide from the air and, with the help of sunlight, break it apart. The plant keeps the carbon to build the compounds that make up all living things, and it releases the oxygen we breathe. This is the process called photosynthesis.
But sunlight and carbon aren’t enough for a plant to grow strong or produce nutritious food. It still needs minerals—calcium, magnesium, potassium, and dozens of others. Those nutrients are locked inside the tiny rock particles and organic matter in the soil. The question is: how do plants actually get to them? For plants to use these nutrients, they have to be dissolved in water—they have to be soluble. And that’s where soil biology steps in.
What do you mean by soluble?
Soluble simply means that one substance can dissolve into a liquid. Think about what happens when you stir salt into a glass of water—it disappears into the water instead of sitting on the bottom. In that dissolved state, the salt breaks apart into its individual pieces, sodium and chloride, and those tiny particles are now floating freely in the water. That’s the form plants can actually take up and use.
The tricky thing about salts is what happens after the water dries up. When the moisture disappears, the salts pull themselves back together into crystals. In that process, they actually trap water molecules, making it harder for plants and soil organisms to access the moisture they need. And because all inorganic fertilizers are salts, they behave the same way. If it rains, they wash out of the soil. If it’s dry, they can harden into a crust on the surface. A plant might get a little sodium or other nutrients from them, but without available water—for the plant or the microbes—everything starts to struggle.
But nature has already designed a much smarter system. The nutrients plants need are already in the soil’s mineral particles and organic matter. The challenge is unlocking them. Plants can’t break down sand, silt, or clay on their own—they don’t have the enzymes for that. This is where microorganisms step in.
Hello, DoorDash?
Plants expend a lot of their energy making sugars—simple carbon chains— as well as other compounds like carbohydrates and proteins. They then release some of these substances into the soil. These are called exudates. Think of exudates as the plant’s way of putting in a Door Dash order to the soil community: “Hey, I’m hungry—come help!” The more exudates a plant sends out, the more bacteria and fungi gather around its roots.
Once those microbes arrive, they get to work. They’re the ones with the enzymes needed to break down tiny soil particles and organic matter, unlocking nutrients like calcium and sodium that the plant can’t access on its own. This is where the soil food web really kicks in, because every organism plays a role in delivering nutrients back to the plant.
Bacteria and fungi eat the exudates. Then the next level of the food web—protozoa and nematodes—eat the bacteria and fungi. When they digest that meal and release their waste, the excess nutrients come out in a soluble form, right in the root zone, exactly where the plant can use them. In other words, they take what they need and “poop out” the rest in a plant-ready package.
In a healthy soil, nothing goes to waste. What one organism releases becomes food for another, and that constant cycling—powered by plant exudates and microbial digestion—is what ultimately feeds the plants we eat.
Soil become self-sustaining
When all the pieces of a living soil system are in place, plants can meet their nutritional needs through their partnership with the soil food web. They don’t need outside inputs because the biology is constantly breaking down minerals, cycling nutrients, and delivering them right to the root zonec—the soil food web is fully intact, nutrient cycling is continuous, and the system sustains itself unless something disrupts it.
Healthy Soil, Healthy Food, Healthy Planet
A balanced soil food web becomes a self-regulating engine. It releases nutrients at the pace plants actually need, which means richer flavor and higher nutrient density for the animals and people who depend on those plants. If you are interested in more information about the bond between soil and food health, I highly recommend, “What Your Food Ate: How to Heal Our Land and Reclaim Our Health.” One of its co-authors, Anne Biklé, will be speaking on this topic at the upcoming meeting at Delaware Valley University, in Doylestown PA on 4/9. You can find more details and register for this event here!
Finally, the benefits of a healthy soil food web don’t stop at nutrition. A healthy soil food web also improves the entire ecosystem by holding water, preventing runoff and leaching, storing carbon, suppressing disease, reducing weeds and pests, maintaining aerobic conditions, deepening root systems, building soil structure, and even breaking down toxins. All of these functions work together to create resilient soil that supports healthy plants and a stable climate.
Sources:
Promotes biodiversity and resilience. https://fity.club/lists/i/images-of-food-chain/
https://www.grow-it-organically.com/soil-food-web.html
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