Soil Erosion

Primary reference(s)

FAO, 2020. Global Symposium on Soil Erosion. Food and Agricultural Organization of the United Nations (FAO). Accessed 20 October 2020.

Additional scientific description

Soil erosion occurs naturally under all climatic conditions and on all continents, but is significantly increased and accelerated by unsustainable human activities (up to 1000 times) through intensive agriculture, deforestation, overgrazing and improper land use changes. The Status of the World’s Soil Resources report identified soil erosion as one of the major soil threats (FAO, 2015a). Soil erosion rates are much higher than soil formation rates; soil is a finite resource, meaning its loss and degradation is not recoverable within a human lifespan (FAO, 2020).

Soil erosion decreases agricultural productivity, degrades ecosystem functions, amplifies hydrogeological risk such as landslides or floods, causes significant losses in biodiversity, damage to urban infrastructure and, in severe cases, leads to displacement of human populations (FAO, 2020).

Soil erosion and land degradation pose a major threat to global food security and to the achievement of the Sustainable Development Goals (SDGs) (UN, 2015) on ensuring the well-being of at least 3.2 billion people around the world (FAO, 2020).

Soils are an essential and non-renewable natural resource hosting goods and services vital to ecosystems and human life. Soils are fundamental for producing crops, feed, fibre, fuel, and they filter and clean tens of thousands of cubic kilometres of water each year. As a major storehouse for carbon, soils also help regulate emissions of carbon dioxide and other greenhouse gases, which is fundamental for regulating climate (FAO, 2017).

The World Soil Charter presents a series of nine principles that summarise current understanding of the soil, the multi-faceted role it plays, and the threats to its ability to continue to serve these roles (FAO, 2015b):

• Principle 1: Soils are a key enabling resource, central to the creation of a host of goods and services integral to ecosystems and human well-being.
• Principle 2: Soils result from complex actions and interactions of processes in time and space and hence are themselves diverse in form and properties and the level of ecosystems services they provide.
• Principle 3: Soil management is sustainable if the supporting, provisioning, regulating, and cultural services provided by soil are maintained or enhanced without significantly impairing either the soil functions that enable those services or biodiversity.
• Principle 4: The implementation of soil management decisions is typically made locally and occurs within widely differing socio-economic contexts.
• Principle 5: The specific functions provided by a soil are governed, in large part, by the suite of chemical, biological, and physical properties present in that soil.
• Principle 6: Soils are a key reservoir of global biodiversity, which ranges from micro-organisms to flora and fauna. This biodiversity has a fundamental role in supporting soil functions and therefore ecosystem goods and services associated with soils.
• Principle 7: All soils – whether actively managed or not – provide ecosystem services relevant to global climate regulation and multi-scale water regulation.
• Principle 8: Soil degradation inherently reduces or eliminates soil functions and their ability to support ecosystem services essential for human well-being.
• Principle 9: Soils that have experienced degradation can, in some cases, have their core functions and their contributions to ecosystem services restored through the application of appropriate rehabilitation techniques.

Metrics and numeric limits

Of the Earth’s soils, 33% are already degraded and over 90% could become degraded by 2050 (FAO, 2015a, 2020).

Worse, most future land degradation is predicted to occur in the areas with the largest amount of arable land remaining. If current trends continue, experts estimate that by 2050, more than 90% of the Earth’s land areas will be substantially degraded, 4 billion people will live in drylands, 50–700 million people will be forced to migrate, and global crop yields will be reduced by an average of 10% and up to 50% in some regions (Nachtergaele et al., 2012 cited by Little, 2019; IUCN, 2015; Gomiero, 2016; IPBES, 2018).

A total of 75 billion tons of fertile soil is removed every year from the global soilscape by erosion. As a result, precious soil resources, which should be preserved for future generations, are continuously reduced. Every year approximately 12 million ha of land are lost (FAO and IAEA, 2017).

Examples of drivers, outcomes and risk management

Because 95% of the food consumed globally comes from the soil, soil erosion mitigation through the application of sustainable soil management (SSM) is critical for protecting soil while ensuring a sustainable and food secure world (FAO, 2020).

Sustainable soil management is an integral part of sustainable land management, as well as a basis for addressing poverty eradication, agricultural and rural development, promoting food security and improving nutrition. Sustainable soil management is a valuable tool for climate change adaptation and a pathway for safeguarding key ecosystem services and biodiversity. Due to the incalculable value soils provide to society through ecosystem services, widespread adoption of sustainable soil management practices generates multiple socioeconomic benefits, especially for smallholder farmers and large-scale agricultural producers worldwide whose livelihoods directly depend on their soil resources (FAO, 2017).

The Status of the World’s Soil Resources report identified ten key threats that hamper the achievement of sustainable soil management. These threats are soil erosion by water and wind, soil organic carbon loss, soil nutrient imbalance, soil salinisation, soil contamination, acidification, loss of soil biodiversity, soil sealing, soil compaction and waterlogging. These threats vary in terms of intensity and trend depending on geographical context, although they all need to be addressed in order to achieve sustainable soil management (FAO, 2017).

One of the key messages from the Assessment Report on Land Degradation and Restoration prepared by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services is to eliminate perverse incentives that promote degradation and to devise positive incentives that reward the adoption of sustainable land management practices in order to avoid, reduce and reverse land degradation (IPBES, 2018).