“Keep soil alive, protect soil biodiversity”. This is the slogan of World Soil Day 2020, an event held on December 5 each year to remind people about the importance of healthy soil and support the sustainable management of its resources.
Suggested by the International Union of Soil Sciences in 2002, World Soil Day was born in Thailand in collaboration with the Global Soil Partnership. And it is precisely with the support of FAO – which approved it in 2013 – that the General Assembly of the United Nations designated the first official day on December 5, 2014.
Now in its seventh year, World Soil Day aims to raise public awareness of the importance of maintaining healthy ecosystems for human well-being. This year the slogan focuses in particular on “underground workers”, i.e. all those organisms that work together in the soil to support life on Earth. Soil biodiversity, which represents 25% of that of the entire planet, is however being lost.
Mushrooms, pill woodlice and moles
According to the European Commission, which promoted an analysis of soil biodiversity and a campaign for its protection in 2010, soil organisms, ranging from single-celled microorganisms to small mammals that burrow into the ground, work together to carry out essential tasks for the Earth to function: they create and regenerate the soil, decomposing organic matter to maintain its productivity; allow the soil to store and release carbon, helping to regulate the climate; purify the water that seeps into the ground, removing contaminants and pollutants, and provide the necessary structures to retain and store it in the soil itself and in aquifers. The complex ecosystem of the soil controls parasites: the richer the biodiversity, the greater the number of predators and, consequently, the lower the possibility of one species dominating the others. Microorganisms provide the means to fight infectious diseases: for example, penicillin, discovered by Alexander Fleming in 1928, is an antibiotic substance obtained from a soil fungus.
The rapid evolution of soil microorganisms makes it a valuable source of new life-saving drugs – a kind of medicine cabinet for the future. The smallest (but also the most important) inhabitants of the subsoil are bacteria, fungi and algae. These “chemical engineers” regenerate the soil by transforming waste organic matter into its individual chemical constituents, thus providing plants and animals with the nutrients they need. A bigger group of slightly larger creatures, the “biological regulators”, keep microorganisms under control, regulating their proliferation and activity.
Earthworms, ants, termites, pill woodlice and mammals such as moles all fall into a third category of soil workers: “ecosystem engineers”. They are responsible for mixing and moving soil particles in order to create habitats for smaller species and allow air and water to seep into the soil. Larger animals, such as voles, rabbits and badgers, who spend only part of their lives in the soil, also help to provide this service.
Together to preserve soil biodiversity
Several initiatives can be taken to stop the loss of soil biodiversity, even by individuals, such as reducing the amount of waste or recycling as much as possible. Changes in the land use, certain invasive species, pollution, urbanization and waterproofing of surfaces (for example due to asphalt) all contribute to biodiversity loss.
Biodiversity is an essential component of the soil, which contains huge amounts of organic material, which is the basis of food production. This material increases its porosity, allowing the storage of water and air, and its ability to store and release nutrients.
Precisely because soil sequesters carbon from the atmosphere and reduces greenhouse gas emissions, the loss of its ability to act as a deposit could increase emissions and accelerate climate change. Work is therefore needed to preserve storage capacity, supporting the adoption of sustainable and biodiversity-friendly soil management practices, particularly in agriculture.