How we monitor soil

Soil monitoring is carried out to gather information about the state of Scotland’s soil quality. Repeated sampling of the same sites is required to detect changes occurring within soils as a result of changing land use, management effects and environmental changes (e.g. climate change).

In the State of the Environment Soil Quality Report (2001), we identified that the application of waste to land was one of the main pressures affecting soil quality. It was noted that there was a lack of data regarding trends in soil properties, making it impossible to assess whether current land use practices and pollutant inputs to soil could be sustained. For these reasons, we believed a comprehensive monitoring programme was required to assess the status of Scotland’s soils, with continual monitoring required to identify changes in soil quality.

We have since developed a risk-based soil compliance monitoring strategy for activities that we regulate that have an impact on soil. Sampling sites where exempt organic waste has been applied are selected on the basis of concerns raised by staff. Sites where sewage sludge has been applied are selected using a risk assessment based on data recorded in the sludge registers provided to us by sludge operators.

We began soil sampling in 2007 and have continued sampling in subsequent years. We intend to resample a proportion of all sites on a regular basis to provide trend information. Results are provided in an annual report.

Soils are sampled by staff using our soil sampling method and are then analysed for a number of soil quality indicators, these being:

• soil acidity (pH);
• carbon (C);
• total nitrogen (N) and carbon to nitrogen ratio;
• extractable phosphorous (P);
• extractable potassium (K) and magnesium (Mg);
• potentially toxic elements;
• microbial biomass carbon;
• earthworms.

A map of all the sites sampled so far can be found here.