• The health of soils is dependent on the variety of organisms they contain, known as soil biodiversity.
• The amount of soil biodiversity determines the productivity of land, and thus the provision of food, water, and the regulation of climate.
• Current land degradation, chiefly due to chemical-fuelled, intensive agricultural production, is causing the loss of soil biodiversity, undermining the services provided by healthy soils.
• Governments should put in place policies and legislation, and promote land management practices which restore or preserve soil biodiversity.
Globally, soil biodiversity has been estimated to contribute between US$1.5 and 13 trillion annually to the value of ecosystems services – the goods and services provided by healthy ecosystems, including the provision of food, hydrological services and regulation of climate.
Food and water security
Soil organisms regulate nutrient availability and uptake of nutrients by plants, maintain soil structure, and regulate hydrological processes. The loss of healthy soils reduces agricultural yields and could result in a food production shortfall of 25% by 2050. It is estimated that increasing soil biodiversity could contribute up to 2.3 billion tonnes of additional crop production per year, valued at US$1.4 trillion.
Research in Argentina, India, and the West African Sahel has also found that crop yields can be increased by 20–70 kg/ha for wheat, 10–50 kg/ha for rice, and 30–300 kg/ha for maize with every 1000 kg /ha increase in soil organic carbon around plant roots.
Soil stores two thirds of the fresh water on the planet, and this function is determined by the level of organic matter in the soil. This water from soils supports 90% of the world’s agricultural production. The loss of soil biodiversity reduces the infiltration capacity of the soil as well as its capacity to store water, lowering food production and worsening the impact of drought. By 2025 an estimated 1.8 billion people will be living under water stressed conditions. One estimate suggests that the loss of 1 g of soil organic matter decreases soil available moisture by 1 to 10 g.
Climate change mitigation
Soil biodiversity represents one of the largest carbon stocks on Earth and plays a major role in mitigating climate change. It is estimated that there is more carbon stored in soils than the total carbon in both the atmosphere and above-ground vegetation. When soil is eroded, the carbon in soils is lost in the form of greenhouse gasses (GHGs), contributing to climate change. Increasing soil biodiversity could provide at least half of emissions reductions needed to limit the global average temperature increase to well below 2°C above pre-industrial levels as set by the Paris Agreement.
Target 15.3 of the UN 2030 Agenda for Sustainable Development aims to halt the world’s net land degradation. Healthy soils are both a natural resource and a public good underpinning sustainable development. The targets of the 2030 Agenda for food, water and energy security, biodiversity conservation and climate change mitigation all hinge on healthy soils. For instance, research has estimated that restoring only 12% of degraded agricultural land by 2030 could boost smallholders' incomes by US$35-40 billion per year and help to feed an additional 200 million people annually, while increasing resilience to drought and water scarcity and reducing GHG emissions.