How Soil Biota Creates and Sustains the World Beneath Our Feet
Soil is much more than just dirt. Beneath the earth's surface lies an incredibly complex ecosystem that scientists are only beginning to understand. In one cubic centimeter of healthy soil, there can be millions of microorganisms, tens of thousands of small invertebrates, and fungal hyphae stretching for several kilometers! This hidden life doesn't just inhabit the soil—it actively shapes it, creating what soil scientists call the "soil profile"—a characteristic layered structure unique to each soil type 5 .
Microorganisms per cm³
Of fungal hyphae
In a typical soil profile
The study of biota's role in creating and functioning soil is experiencing a true revolution. New research shows that soil organisms are not just inhabitants, but architects and engineers whose activities determine the very structure of the soil profile, its physical and chemical properties, and ultimately, the fertility of the entire planet 5 8 . In this article, we explore how biota creates and maintains the soil profile and get acquainted with the latest discoveries in this fascinating field of science.
The soil profile is a combination of genetic horizons characteristic of each natural soil formation type. It forms as a result of differentiation of the original soil-forming rock under the influence of soil formation processes and characterizes changes in all soil properties vertically 1 . Simply put, if we make a deep cut in the soil down to the parent rock, we'll see a sequence of layers, each with its own characteristics and performing certain functions 6 .
| Horizon | Name | Depth | Main Functions | Characteristic Organisms |
|---|---|---|---|---|
| A0/O | Forest litter/steppe felt | 0-5 cm | Accumulation of organic litter | Saprophages, decomposer fungi |
| A/A1 | Humus/humus-accumulative | 5-50 cm | Humus accumulation, maximum biological activity | Earthworms, bacteria, mycorrhizal fungi |
| A2 | Eluvial | 10-70 cm | Leaching of substances to underlying horizons | Aerobic bacteria, fungi |
| B | Illuvial | 50-150 cm | Accumulation of substances washed from above | Anaerobic microorganisms, tree roots |
| C | Parent rock | >100 cm | Source of mineral substances | Rare chemolithotrophic microorganisms |
Key Insight: Traditionally, soil horizons were considered mainly from the perspective of their physical and chemical properties. However, modern research shows that it is biota that plays a key role in creating and maintaining this layered structure 4 . Each horizon is the result of the activity of a specific community of organisms adapted to certain conditions at different depths.
What if soil is not just a mechanical mixture of minerals and organic matter, but a complex biological system? This revolutionary hypothesis was put forward in the 1980s by Doctor of Physical and Mathematical Sciences Alexey Ivanovich Morozov. According to his idea, the biota of natural soil forms a hierarchical information and transport system controlled by a small number of "monarch" organisms 5 .
Small number of organisms that control the hierarchical information and transport system of soil biota according to Morozov's hypothesis 5 .
"Social complexes" where strong plants transfer photosynthesis products to weaker ones through mycorrhiza 5 .
This hypothesis has found unexpected confirmations. In the USA and Europe, honey fungi were discovered whose mycelium covers areas of many hectares and is several thousand years old. In Sweden, a "social complex" of organisms was found where strong plants pump their photosynthesis products to weak ones through mycorrhiza 5 . These discoveries force us to look at the role of biota in soil formation and functioning in a new way.
Breaking down plant and animal remains that enter the soil 8 .
Partial mineralization and conversion into humus substances 8 .
Enriching soil with nitrogen through nodule and free-living bacteria 8 .
Transporting and mixing substances throughout the soil profile 8 .
Forming stable granular soil structure that determines water-air regime 8 .
Secreting physiologically active compounds that affect nutrient availability 8 .
Fungi play a special role in organizing the soil ecosystem. It is their mycelium that forms extensive networks that can serve as transport and information highways, connecting different parts of the soil profile into a single whole 5 .
The total length of fungal hyphae in a cubic centimeter of soil can reach hundreds or even thousands of meters. If we mentally cut a kilometer of hyphae into centimeter segments and distribute them evenly, the distance between adjacent segments would be only about 30 microns—enough to cover almost the entire soil volume 5 .
Mycorrhiza—a symbiotic association of fungi with plant roots—represents one of the key elements of soil biota organization. It performs many functions 5 :
Fungal mycelium creates extensive networks that serve as transport and information highways in soil 5 .
Interestingly, unlike plant roots, which mainly form soil structure and supply organic matter, it is fungi that in many cases coordinate the activities of the entire soil ecosystem, making them the main candidates for the role of those "monarchs" controlling the soil "polis" 5 .
Mycorrhiza represents a symbiotic relationship between plant roots and fungi, creating a mutually beneficial exchange system 5 .
Fungal networks facilitate communication between plants through chemical signals, allowing for coordinated responses to environmental changes 5 .
One of the promising directions in modern soil science is the development of bioremediation methods—cleaning soils from pollutants using biological agents. Researchers from Southern Federal University (Rostov-on-Don) conducted an experiment on creating and applying enhanced biochar to remove heavy metals from soil 2 .
Obtaining biochar from wheat straw—a waste remaining after harvest 2 .
Synthesizing metal-organic framework (iron-containing) from iron powder and organic acid 2 .
Creating nanocomposite by mixing components and holding for 20 minutes at 120°C 2 .
Introducing nanocomposite into soil samples previously contaminated with known amounts of lead and copper 2 .
Comparative analysis of nanocomposite effectiveness versus regular biochar 2 .
Study of the obtained material structure showed that the metal-organic framework increased the surface area of biochar six times by creating additional pores. This sharply increased the material's ability to "collect" heavy metals 2 .
It turned out that the nanocomposite removes up to 99% of heavy metals from soil even at their high content in samples, while for regular biochar at high contamination, effectiveness drops to 82% 2 .
| Sorbent Type | Effectiveness at Low Contamination | Effectiveness at High Contamination | Surface Area | Main Binding Mechanisms |
|---|---|---|---|---|
| Regular Biochar | 90-95% | 82% | Basic | Physical adsorption |
| Nanocomposite Biochar + MOF | 98-99% | 99% | 6x larger | Complexation, ion exchange, adsorption |
Metals form complexes with oxygen-containing groups in the metal-organic framework composition 2 .
Exchange of cations occurs between iron-containing centers in the composite and contaminated soil 2 .
| Parameter | Before Treatment | After Nanocomposite Treatment | After Regular Biochar Treatment |
|---|---|---|---|
| Lead Content | 100% (high concentration) | 1% | 18% |
| Copper Content | 100% (high concentration) | 1% | 17% |
| Biological Activity | Suppressed | Restored by 85-90% | Restored by 60-70% |
| Soil Structure | Disturbed | Significantly improved | Moderately improved |
This research demonstrates how understanding the role of biota in soil functioning allows creating innovative methods for restoring disturbed soils. The developed material can be used for restoring soils heavily contaminated with heavy metals near large metallurgical plants, roads, and chemical enterprises 2 .
Studying the role of biota in soil profile formation requires special methods and materials. Here are the main "tools" used in this field:
| Reagent/Material | Composition/Characteristics | Function in Research | Example Application |
|---|---|---|---|
| Biochar | Carbon material from biomass | Pollutant sorption, soil property improvement | Base for creating sorption materials |
| Metal-Organic Frameworks | Coordination polymers from metal ions and organic ligands | Creating highly porous structures with sorption capacity | Increasing biochar surface area |
| Selective Nutrient Media | Agar media with specific additives | Isolation and cultivation of specific microorganism groups | Assessment of soil microbiota diversity |
| Fluorescent Probes | Labeled antibodies or oligonucleotides | Visualization of microorganisms in situ | Studying spatial distribution of biota in profile |
| Stable Isotopes | 13C, 15N, 18O | Tracing substance and energy flows | Researching trophic connections in soil ecosystem |
Advanced imaging techniques to visualize soil microorganisms and their interactions.
Molecular techniques to identify and characterize soil microbial communities.
Statistical and computational methods to interpret complex soil ecosystem data.
Studying the role of biota in creating and functioning the soil profile is not just an academic interest. Understanding these processes has key importance for solving urgent contemporary problems: ensuring food security, combating climate change consequences, developing effective methods for restoring disturbed lands 2 5 .
Soil biota is not just a soil inhabitant, but its creator and guardian. From microscopic bacteria to extensive fungal networks—all these organisms work in concert, forming the complex structure of the soil profile on which terrestrial life depends.
As Alexey Morozov rightly noted, today soil science is a "modest, predominantly descriptive science," an "ugly duckling" destined to turn into a "magnificent swan" 5 . It is already clear that in the 21st century, soil and related systems will receive attention no less than informatics, biology, nanotechnology, astronautics, and other advanced scientific directions.
Understanding how biota creates and maintains the soil profile opens new horizons for developing sustainable agriculture, remediation of contaminated areas, and creating closed ecological systems. Soil, this giant and completely mysterious world, gradually reveals its secrets, offering us wise solutions to the most acute environmental problems 5 .
Understanding soil biota enables development of sustainable agricultural practices that work with natural processes rather than against them.
Soil biota knowledge provides tools for restoring degraded ecosystems and reversing environmental damage.