What Is Living Soil? A Beginner’s Guide to Soil Microbial Ecosystems

Written By Erik Vegeto

You may have heard of "living soils" in cannabis cultivation and wondered what it’s all about. Though the term may sound far out, it’s a method used to improve soil fertility that is based on the science of natural ecosystems that have evolved over millions of years. While scientists like Dr. William Albrecht formalized our understanding of living soil in the early 1900s, the principles reflect processes that existed long before modern horticulture.

In nature, soil is a dynamic system—an ecosystem where plants, microorganisms, organic matter, air, water, and minerals work together synergistically to create a cohesive whole. In indoor cultivation, especially in regenerative systems, living soil replicates these natural processes in a managed environment.

By understanding what goes into making a soil in nature, we can create a self-sustaining micro-ecosystem in a container with all the resilience and fecundity of nature.

Source: wikipedia commons


The Origins of Living Soil

To understand living soil, let’s take a step back in time. Before plants appeared on Earth, the land was barren during the Silurian period; it was rocky with exposed minerals, and pock-marked with volcanoes and jagged mountain ranges. Around 420–360 million years ago, Earth’s landmasses were unrecognizable, with no vegetation to create the lush, diverse landscapes we know today. The atmosphere was thick with carbon dioxide and methane, and without plants to help form soil, the Earth’s surface was largely devoid of the rich, brown, sweet-smelling, fertile earth we take for granted.

The arrival of plants changed everything. Early colonizers from the oceans like cyanobacteria and mosses played a key role in transforming the barren parent materials of the land into fertile soil. Plants helped break down minerals by using organic acids (such as citric and oxalic acids), which helped create sand, silt, and clay. They were also aided by larger physical processes such as hydrological (water) weathering. As plants drew nutrients from the minerals they broke down, they enriched the mineral components by adding carbon compounds—organic matter, such as is found in decaying leaves. This created a kind of doughy glue that held the mineral particles together. This is the basis of soil structure and is key in creating a soil with balanced qualities of aeration, water-retention, and nutrient-holding capacity.

When you look at a clump of plant roots you’ll see a small illustration of the ancient process. Plant roots trap mineral components and organic matter in a web of stringy capillaries and mineral architecture as they draw from it both water and nutrients. Through exudates—which are carbohydrates and other chemicals secreted by plant root systems—plants regulate the chemistry of the soil they are growing in. They will even regulate microbial populations in the soil by producing compounds that suppress unwanted organisms and stimulate the growth of beneficial organisms. Over time, plants work the biotic (living) and abiotic (non-living) components of the soil to create a rich sub terrestrial ecosystem which is well-suited for their particular style of growth.

Creating a living soil in your grow setup is about providing the right soil ingredients—both biotic and abiotic—and creating a hospitable environment (i.e. temperature, humidity, CO2, water), so that your plants, and the organisms that support their growth, can successfully colonize the physical substrate of the soil. Often, it is a matter of if you build it, they will come. Organisms want to thrive and transform their soil environment; it’s your job to set the table for them.

Have a look at this recipe for creating a living soil: Living Soil 101. Here you will find a good entryway into getting experience with growing in a living soil. 

Perhaps the reason why living soil is, more than just a science, an art, is because you must get direct, sensory feedback from the soil—how it smells, looks, feels, and affects plant growth—to make the right adjustments to support the specifics of your particular grow op. Quantification of these variables and the use of statistics is profoundly helpful, allowing you to precisely diagnose issues and take informed action—but don’t forget to use your gut. You must experiment with soil ingredients, introduce soil organisms, optimize your grow environment, and reflect upon a host of other variables to find a balance. This is the heart of a functioning, fertile, and resource-efficient ecosystem, and it is not built overnight. It is the result of layers of experience—generations of organismic adaptation, evolution. 

By building a living soil that mirrors the precipitant, spontaneous structuring of natural soil ecosystems, you are participating in the elegant process of organisms—plants, fungi, bacteria, animals, and others—creating a habitat for themselves and others. 

When soil organisms are balanced—organized in the structure of an ecosystem—they form an emergent whole which is greater than the sum of its parts.

Sources:

Albrecht, W. A. (1938). "Soil Fertility and Animal Health." (Missouri Agricultural Experiment Station).

Nature Education. (n.d.). What are soils? Nature Scitable. Retrieved February 8, 2025, from https://www.nature.com/scitable/knowledge/library/what-are-soils-67647639/

Wikipedia contributors. (n.d.). Silurian-Devonian Terrestrial Revolution. Wikipedia, The Free Encyclopedia. Retrieved February 8, 2025, from https://en.wikipedia.org/wiki/Silurian-Devonian_Terrestrial_Revolution


Natural Resources Defense Council. (n.d.). Regenerative agriculture 101. NRDC. Retrieved February 8, 2025, from https://www.nrdc.org/stories/regenerative-agriculture-101


Natural Resources Defense Council. (n.d.). Regenerative agriculture 101. NRDC. Retrieved February 8, 2025, from https://www.nrdc.org/stories/regenerative-agriculture-101


OpenStax. (n.d.). Weathering and the formation of soil. In Physical geology (2nd ed.). Retrieved February 8, 2025, from https://opentextbc.ca/physicalgeology2ed/chapter/5-4-weathering-and-the-formation-of-soil/

University of Nebraska–Lincoln. (n.d.). Connection between soil organic matter and soil water. Nebraska Extension. Retrieved February 8, 2025, from https://water.unl.edu/article/animal-manure-management/connection-between-soil-organic-matter-and-soil-water/

Ghosh, R., & Mathew, S. (2021). Role of root exudates in shaping the soil microbiome and improving soil health. Frontiers in Microbiology, 12, 711231. https://doi.org/10.3389/fmicb.2021.711231

Wikipedia contributors. (n.d.). Plant–soil feedback. Wikipedia. Retrieved February 8, 2025, from https://en.wikipedia.org/wiki/Plant%E2%80%93soil_feedback

Lowenfels, Jeff, & Lewis, Wayne (2006). Teaming with Microbes: The Organic Gardener's Guide to the Soil Food Web. Timber Press.

Further Readings: The Living Soil by Lady Eve Balfour

Erik Vegeto

Erik Vegeto has been passionate about growing since he was young, with a deep fascination for botany, biology, and chemistry. His love for plants and the natural world was complemented by his creative pursuits in music, songwriting, and performance. After earning a degree in Plant, Soil & Insect Science from UMass Amherst's Stockbridge School of Agriculture, Erik spent over five years honing his skills in the green industry, working in nurseries and high-tech cannabis greenhouses as both a technician and manager. Today, he is the proud owner and operator of Earth Gardeners, a business focused on sustainable horticultural practices and ecological development. With expertise in plant science, pest management, and cannabis cultivation, Erik continues to share his knowledge and passion with others, empowering them to grow in harmony with nature.

http://earthgardeners.org/