Although soils are vital for agriculture, biodiversity, and clean water, this below-ground world is often overlooked. The loss of life below the ground due to intensification of agriculture, climate change, erosion, and compaction, among other things, is one of the biggest global threats to soils.
Many organisms live in the soil. In fact, about 25% of all biodiversity occur in the soil. These organisms do not function in isolation but interact with each other and the above-ground world in complex ways. They provide essential services and benefits such as the breakdown of leaf litter for nutrient cycling, play a role in the formation of soil structure, and clean water and air through the soil layers.
With an increase in extreme events such as heatwaves and droughts due to climate change, soil is becoming increasingly degraded worldwide. Organisms and the soils they live in are dying. Another reason is the increased demand for food production through more intensive agriculture, and compaction – when soil particles are pressed together, reducing the space between soil particles – reduces water infiltration and air in the soil.
But if there is a change in how soils are managed, more resilient, and sustainable soils can be created that can survive these increasing extreme events and enhance food security. This means soil will recover after extreme events. It will not need so many fertilisers and pesticides and will be able to maintain long-term production of high quality food.
The theme for World Soil Day on 5 December 2020 was: “Keep soil alive, protect soil biodiversity.” It coincided with the release of the State of Knowledge of Soil Biodiversity report. This report, facilitated by the Food and Agriculture Organisation of the United Nations (FAO), involved more than 300 scientists from around the globe, me included. It highlights the rich diversity of soil organisms under our feet that drive processes that produce food and purify soil and water.
Soil biodiversity in Africa
Soils are the most biologically diverse habitat on earth. One gram of soil contains several thousands of different species. More than 40% of all land organisms have their life cycle, or part of it, in the soil. These range from the smallest microbes, fungi, and nematodes, to mites, springtails, centipedes, millipedes, potworms, various insects such as ants and termites, larger arthropods such as millipedes, spiders and woodlice, and even larger vertebrates such as moles and reptiles.
Over the past few decades there has been an increased interest in soil health globally and in South Africa. This comes after events such as massive droughts, erosion and studies of the function that soil organisms play in soil health and increased awareness campaigns.
Despite South Africa being only 0.8% of the earth’s terrestrial area, it contains nearly 1.8% of the world’s described soil species. South African soils contain a very high number of species that occur nowhere else in the world, especially nematodes and earthworms, although these are groups that have been studied more than others.The full article is for subscribed members only. To view the full article please subscribe. It’s FREE!Log In Register
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