Biodiverse soils are home to a rich tapestry of soil organisms – there are more microbes in a teaspoon of soil than there are people on earth! The soil community is made up of different trophic levels and functional groups; from microscopic bacteria and fungi to insects and our favourite wiggly friends, earthworms. These critters, large and small, make up the soil food web.
Soil organisms are an essential component in carbon and nutrient cycling, making nutrients available for plant uptake and creating stable forms of carbon stored in the soil. They create aggregated soil structure, allowing water and air, which are essential for plant growth, to percolate through the soil profile. They naturally buffer soil borne pests and diseases, purify water, clean up pollutants and boost resilience to climatic and environmental changes.
Each organism specialises in a particular function which is key to maintaining healthy soil. The whole biological community works together to provide these functions, it is tricky to isolate just a few organisms which are required, really you need a diverse mix. If soil biodiversity goes into decline, soil structure breaks down, leaving it vulnerable to erosion, as soil is unable to soak up moisture, leaving water to run off, taking soil and nutrients with it. Does this sound familiar – have you seen bare patches of soil and muddy water spilling into a nearby stream or river?
Soil biodiversity is declining on many farms due to agricultural intensification and climate change. When we farm soils, we mine nutrients to grow crops, but are we putting these back in a way which improves soil health? Feeding soil with synthetic fertilisers is very disruptive to the soil community, rendering many of their functions redundant. If we begin to take the approach of nurturing our soil community, we will be richly rewarded with all the functions they can provide.
Stay tuned for the next installments in this series to hear more about functions soil biodiversity provide.
European Commission. (2010). The Factory of life: Why soil biodiversity is so important. Retrieved from: https://ec.europa.eu/environment/archives/soil/pdf/soil_biodiversity_brochure_en.pdf
Mujtar, V, E., Muñoz, N., Prack Mc Cormick, B., Pulleman, M., Tittonellad, P. (2019). Role and management of soil biodiversity for food security and nutrition; where do we stand? Retrieved from: https://www.sciencedirect.com/science/article/pii/S2211912418300300?via%3Dihub
Plaas, E., Meyer-Wolfarth, F., Banse, M., Bengtsson, J., Bergmann, H., et al. (2019). Towards valuation of biodiversity in agricultural soils: A case for earthworms. Retrieved from: https://www.sciencedirect.com/science/article/pii/S0921800918304610?via%3Dihub
van Leeuwen, J., Creamer, R., Cluzeau, D., Debeljak, M., Gatti, F., et al. (2019). Modeling of Soil Functions for Assessing Soil Quality: Soil Biodiversity and Habitat Provisioning. Frontiers in Environmental Science, Frontiers, 7, pp.113. Retrieved from: https://hal-agrocampus-ouest.archives-ouvertes.fr/hal-02280390/