The importance of soil
Soil is one of the UK's most precious resources and yet our soils are under threat. Since industrialisation, we have been taking carbon out of the soil in the form of food and textiles and not replacing it at the same rate. To maintain fertility, we use artificial nutrients instead, leaving the soil with a carbon deficit and insufficient water holding capacity. The missing carbon in our soils has ended up in the atmosphere, contributing to climate change and increasing the probability of extreme weather events, such as the 2014 floods in Somerset and the 2007 floods in Carlisle and Yorkshire.
Why we need to regenerate soil
Degraded soil is less capable of delivering essential ecosystem services: food production, provision of public health and wellbeing, flood mitigation and carbon storage. According to the Natural Environment White Paper, all UK soils need to be managed sustainably including successfully tackling degradation threats by 2030. In addition, regenerating brownfield land may also help improve public health and community wellbeing, as communities with large amounts of brownfield tend to have poorer health outcomes.
Benefits of maintaining soil organic carbon
Healthy soils that have sufficient soil organic carbon (SOC) are more resilient to erosion. By absorbing many times its weight in water increasing SOC could contribute to flood mitigation after extreme rainfall events and store water during frequent or severe droughts. Soils are predicted to become warmer which could likely lead to increased soil respiration, making them drier and less stable during extreme weather. This can be counteracted if SOC levels are maintained and enhanced.
The National Adaptation Programme (NAP) lacks specific plans to investigate how to enhance SOC and hence increase its capacity to store water (potential increases in water holding capacity range from 3% to 20%); and its ability to be absorbed by the land to replenish acquifers.
A recent House of Lords report on the Bioeconomy identifies 30 million tonnes of organic wastes produced each year in the UK, which have come from the land but are currently not returned to it. Finding sustainable ways to raise SOC levels using organic wastes is an opportunity that must be explored by soil engineers and scientists in order to safeguard SOC and ensure soil has maximum flood and carbon mitigation potential.
- EU Soil Report 2012
- National Environment White Paper 2011
- Bambra C, et al. (2014) 'Healthy land? An examination of the area-level association between brownfield land and morbidity and mortality in England'. Environment and Planning A 46(2)
- National Adaptation Programme 2013
- Waste or Resource? Stimulating a bioeconomy, House of Lords, Science and Technology Select Commitee, 2014