Richard Young, Stefano Orsini, Ian Fitzpatrick
Sustainable Food Trust
• Research by the Economics of Land Degradation Initiative in 2015 calculated that soil degradation is costing between $6.3 and 10.6 trillion dollars per year globally, but these costs could be reduced by enhancing soil carbon stocks and adopting more sustainable farming methods.
• A research group at Cranfield University estimated that in England and Wales soil degradation costs £1.33 billion annually. Half of this cost relates to loss of soil organic carbon (SOC), and the intensity of farming is a major cause of soil carbon loss.
• Land use change can significantly reduce soil organic carbon and increase carbon dioxide (CO2), nitrous dioxide (NO2) and methane (CH4) emissions. Changing land use from pasture to cropland results in the greatest loss of SOC.
• Farming practices can be employed to improve soil quality and increase soil carbon, including optimal fertilisation, crop-grassland rotation, hedgerow planting and animal manure application. The effects of other practices to SOC stocks, like no-till and green manures, are debated: recent studies show that their contribution is often limited, and in many situations no-till actually leads to yield declines compared with conventional tillage systems.
• In arid and semi-arid regions, salt-induced soil degradation is one of the most widespread soil degradation processes. It has been estimated that over the last 20 years, 2,000 hectares of agricultural land per day, an area the size of France, has been lost due to salinisation. This is equivalent to a global economic loss of $27.3 billion per year. Efficient water management, along with better fertiliser use and improved crop varieties could significantly reduce the negative effects of saltinduced soil degradation.
• Given the technological advances that have been made in recent years and the greater scientific understanding of the issues today, all types of soil degradation are potentially reversible, as long as there is sufficient public support, understanding and political will.