The Soil Food Web - A TerraSoil Overview
TerraSoil
03 Aug 2024
Harnessing the Soil Food Web for Enhanced Growth
What is the Soil Food Web?
The soil food web is a complex network of interactions among organisms inhabiting the soil, including: bacteria; fungi; protozoa; nematodes; micro-arthropods; and earthworms. These organisms engage in a variety of trophic relationships, where energy and nutrients are transferred from one organism to another through predation, decomposition, and symbiosis.
Some Soil Food Web Species and Their Roles
Species | Role in Soil | What It Eats | What Eats It | Trophic Level |
Bacteria | Decomposers, Nutrient Cyclers | Organic Matter, Detritus, Minerals | Protozoa, Nematodes | Primary Consumers |
Fungi | Decomposers, Mycorrhizal Symbionts | Organic Matter, Detritus, Minerals, Plant Roots | Bacteria, Nematodes | Primary Consumers |
Earthworms | Soil Mixers, Nutrient Cyclers | Organic Matter, Soil Particles | Bacteria, Fungi | Primary Consumers |
Protozoa | Predators, Nutrient Cyclers | Bacteria, Fungi, Algae | Micro-arthropods, Nematodes | Secondary Consumers |
Non-parasitic Nematodes | Predators, Decomposers | Organic Matter, Detritus, Bacteria, Fungi, Protozoa | Predatory Nematodes, Springtails | Primary / Secondary Consumers |
Predatory /Parasitic Nematodes | Predators | Bacteria, Fungi, Protozoa, Nematodes, Insects | Predatory Nematodes, Springtails | Tertiary Consumers |
Plant Nematodes | None | Plants | Predatory Nematodes | Primary Consumers |
Springtails | Detritivores, Soil Structure Engineers | Organic Matter, Fungi, Possibly Secondary consumers | Predatory Mites, Nematodes | Primary /Secondary Consumers – Possibly Tertiary |
Soil Mites | Predators, Detritivores | Fungi, Protozoa, Plant Debris | Springtails, Nematodes | Primary –Secondary Consumers |
Predatory Mites | Predators | Nematodes, Mites, Insect larvae and soft bodied insects | Beetles, some insects | Tertiary Consumer |
Woodlice | Detritivores, Soil Conditioners | Decaying Organic Matter | Fungi, Bacteria, Wasps, Spiders, Centipedes | Secondary Consumers |
Benefits of the Soil Food Web
Nutrient Cycling: Organisms within the soil food web break down organic matter, releasing nutrients that are essential for plant growth and soil fertility.
Soil Structure Improvement: Soil organisms such as earthworms and springtails enhance soil structure through burrowing, mixing, and aggregation, promoting aeration and water infiltration.
Pest Regulation: Predatory organisms such as nematodes and mites help regulate pest populations by feeding on harmful insects, pathogens, and pest larvae.
Plant Health Promotion: Symbiotic relationships between plants and mycorrhizal fungi facilitate nutrient uptake, enhance plant growth, and improve stress tolerance.
How to Use the Soil Food Web to Our Benefit
Farmers and gardeners can harness the power of the soil food web to enhance soil health and agricultural productivity through practices such as:
Incorporating organic matter: Adding compost, mulch, and cover crops enriches soil organic matter, providing food and habitat for soil organisms.
Minimizing disturbance: Reduced tillage and conservation agriculture practices preserve soil structure and microbial diversity, promoting a healthy soil food web.
Promoting biodiversity: Diverse crop rotations, inter-cropping, and agro-forestry systems support a rich diversity of soil organisms, enhancing ecosystem resilience and productivity.
Main Beneficial Soil Fauna Used in Agriculture
Earthworms: These soil engineers enhance soil structure and nutrient cycling through their burrowing and feeding activities.
Mycorrhizal Fungi: Symbiotic associations between plants and mycorrhizal fungi improve nutrient uptake and plant growth.
Predatory Nematodes: These microscopic predators help control pest populations by feeding on harmful insects and other nematodes.
Key Players in the Soil Food Web
Bacteria: Microscopic decomposers and nutrient cyclers that break down organic matter and recycle nutrients in the soil.
Fungi: Decomposers and mycorrhizal symbionts that play vital roles in organic matter decomposition and nutrient uptake by plants.
Springtails: Tiny arthropods that feed on organic matter and contribute to soil aeration and nutrient cycling.
Soil Mites: Predatory and detritivorous mites that regulate soil microbial populations and contribute to organic matter decomposition.
Woodlice: Detritivorous crustaceans that consume decaying organic matter including their own faeces and Fungi. Whilst woodlice do not urinate, they do release ammonia gas through their exoskeleton.
Conclusion
Understanding soil web dynamics, prey-predator relationships, and the interactions between plants and soil organisms is crucial for optimizing growing conditions and ensuring sustainable agriculture. By encouraging the establishment of a functional soil food web, and nurturing the right trophic balance, we can support robust plant growth, enhance soil fertility, and contribute to environmental sustainability.
References
1.     Coleman, D. C., Callaham, M. A., & Crossley, D. A. (2017). "Fundamentals of Soil Ecology" (3rd ed.). Academic Press.
2.     Bardgett, R. D., & van der Putten, W. H. (2014). "Belowground biodiversity and ecosystem functioning." Nature, 515(7528), 505-511.
3.     Fitter, A. H., & Garbaye, J. (1994). "Interactions between mycorrhizal fungi and other soil organisms." Plant and Soil, 159(1), 123-132.
4.     Brussaard, L. (1997). "Biodiversity and ecosystem functioning in soil." Ambio, 26(8), 563-570.
5.     Ingham, E. R., & Wilson, M. V. (1999). "The soil foodweb: Its structure and function." Compost Science & Utilization, 7(1), 75-82.
6.     Lavelle, P., & Spain, A. V. (2001). "Soil Ecology." Springer.
7.     Wolters, V. (2000). "Invertebrate control of soil organic matter stability." Biology and Fertility of Soils, 31(1), 1-19.
8.     Wardle, D. A. (2002). "Communities and Ecosystems: Linking the Aboveground and Belowground Components." Princeton University Press.
9.     Bongers, T., & Ferris, H. (1999). "Nematode community structure as a bioindicator in environmental monitoring." Trends in Ecology & Evolution, 14(6), 224-228.
10. Scheu, S. (2002). "The soil food web: Structure and perspectives." European Journal of Soil Biology, 38(1), 11-20.