Soil Biodiversity in Food Production and Climate Change Mitigation

Role of Soil Biodiversity in Food Production and Climate Change Mitigation

  • Presenter: Dr. Israel Ikoyi

  • Affiliation: School of Biological, Earth, and Environmental Science & Environmental Research Institute, University College Cork

  • Date: 16th February 2026

Soil as a Habitat

  • Components of Soil:
      - Soil particles
      - Organisms Present in Soil:
        - Cysts
        - Amoebas
        - Flagellates
        - Bacterial colonies
        - Nematodes
        - Ciliates
        - Clay-organic matter complexes
        - Decomposing plant cells
        - Water
        - Actinomycete hyphae and spores
        - Fungal hyphae and spores
        - Plant roots

Understanding Soil Biodiversity

  • Concept: Soil Biodiversity
      - Defined as the variety of life belowground, encompassing:
        - Genes and species
        - Communities formed
        - Ecological complexes, from micro-habitats to landscapes

The Importance of Soil

  • Charles E. Kellogg quote:
      - “Essentially, all life depends upon the soil … There can be no life without soil and no soil without life; they have evolved together.”

Soil Organisms

  • Population Estimates in Soil:
      - Example from 1g of soil:
        - >100,000,000 bacterial cells
        - >11,000 species of bacteria
        - Presence of fungi and larger animals

Soil Life Connection

  • Significance of Soil Biodiversity:
      - More than 40% of living organisms in terrestrial ecosystems are directly associated with soils during some life cycle stage.
      - Soils house arguably the most diverse terrestrial communities on the planet, supporting life above ground through well-understood above- and below-ground linkages.

Key Terms Defining Soil Biodiversity

  • Microflora: Bacteria, archaea, algae, fungi (prokaryotes - organisms lacking nuclei and organelles)

  • Macroflora: Plant roots

  • Microfauna: Protozoa, small nematodes, small arthropods (single-celled eukaryotes that are motile)

  • Mesofauna: Metazoans with body sizes typically between 0.1 mm and 2 mm, including larger predatory and omnivorous nematodes

  • Macrofauna: All metazoan invertebrates and chordate phylum members (mammals, amphibians) larger than 2 mm

Data on Soil Biodiversity

  • Diversity Statistics:
      - Bacteria and Archaea: 2.5imes10302.5 imes 10^{30} cells
      - Fungi: 0.8-3.8 million species
      - Nematodes: 4imes10204 imes 10^{20} individuals in soils
      - Mites: 20,000 described species, 80,000 undescribed
      - Collembola: 8,000 described species
      - Earthworms: 6,000 species across 20 families
      - Termites: 2,934 species across 282 genera
      - Ants: 20,000 species

Classification of Soil Organisms

  • Macrofauna: Soil 'engineers' including termites, centipedes, snails, earthworms, etc.

  • Microflora and Microfauna: Includes bacteria, fungi, nematodes

  • Mesofauna: Includes organisms like protozoa, rotifera, and various sizes of nematodes.

The Role of Soil Macrofauna

  • Functions of Soil Macrofauna:
      - 1. Decomposition - shreds residues.
      - 2. Mixing Soil - aeration contribution.
      - Diagram indicating decomposition rate of blue grama (Bouteloua gracilis) over time.

  - Earthworm Classification:
    - Epigeic: L. rubellus (surface-dwelling)
    - Endogeic: A. caliginosa (deep-burrowing)
    - Anecic: A. longa (shallow-burrowing)

Ecosystem Services by Earthworms

  • Ecological Categories:
      - Epigeic (decomposing leaf litter), Anecic (feeding on soil and plant material), Endogeic (shallow-burrowing).

  • Soil Processes:
      - Nutrient cycling, creation of soil pores, soil aggregate formation through secreted mucus.

  • Ecosystem Services:
      - Waste recycling, carbon and nutrient regulation, water flow regulation, maintenance of soil structure.

Role of Soil Mesofauna

  • Types of Soil Mesofauna:
      - Nematodes, Protozoa, Springtails, Mites

  • Functions:
      - Residue decomposition
      - Predation
      - Pathogenesis

Soil Microfauna

  • General Characteristics:

  • Microorganisms that control soil processes, including bacteria and fungi.

Importance of Fungi

  • Filamentous Growth: Critical for ecosystem functions.
      - Roles in wood degradation and forming mycorrhizal associations, enhancing nutrient uptake (phosphate in particular).

Soil Biodiversity and Nutrient Cycling

  • Key for Nitrogen Cycling:
      - Differences in storage demonstrated through anthropogenic and natural components.

Roles of Soil Organisms in Soil Quality

  • Key Processes:
      - Structure/Aggregation
      - Humification
      - Decomposition
      - Nutrient Cycling

Summary of the Beneficial Roles of Soil Organisms:

  1. Nutrient cycling and organic matter cycling

  2. Nitrogen fixation

  3. Nitrification/denitrification

  4. Soil aggregation

  5. Plant growth promotion

  6. Methane production and absorption

  7. Pest control

  8. Water cycle regulation including purification, storage, and transfer

  9. Decontamination and bioremediation

Connection to Sustainable Development Goals (SDGs)

  • Healthy soil is crucial for supporting most terrestrial ecosystem services, contributing to human well-being and sustainable food production.

Challenges in Soil Biodiversity

  • Challenges Identified:
      - Lack of soil biodiversity data at various levels (local to global)
      - Insufficient national soil information systems
      - Absence of global harmonized protocols for sampling and analysis
      - Need for increased focus on soil biodiversity in restoration efforts

Potentialities of Soil Biodiversity

  • Key Benefits:
      - Food security and safety through improved agricultural production
      - Biological pest and disease control
      - Environmental remediation techniques
      - Mitigation/adaptation strategies for climate change

Key Management Actions for Soil Health

  • Maintain regular feeding of soil with organic inputs

  • Optimize water balance, nutrient application, and physical structure

  • Diversify plant life and minimize soil compaction

Managing Soil Biodiversity

  • Emphasize the importance of diversity in response to management interventions

  • Suggests reduced tillage versus plowed soil impact on organism activity and properties

Conclusion

  • Soil is rich in organisms essential for ecosystem functioning.

  • Protecting soil biodiversity is key for maintaining soil function and health, crucial for sustainable food production.

References and Further Reading

  • Figures and diagrams cited from various studies, including original articles from European Journal of Soil Biology, and works from prominent researchers.