The findings from the CAASM research project are now available as a downloadable, open access scientific paper published in the European Journal of Soil Science. We prepared a press release that describes the significance this work.
Policy makers in England and Wales need to know whether important soil properties (or indicators) are changing over time at national scale. This could highlight particular problems in the physical, chemical and biological properties of the soil that determine their fertility and susceptibility to degradation threats such as soil erosion. 2010, the UK government provided funds for this activity to be undertaken as part of the Centre for Ecology & Hydrology project Countryside Survey, and also in the National Soils Inventory undertaken by Cranfield University. Since 2010, such surveys have not been undertaken in part because of insufficient funding.
Farmers frequently request measurements of their soil to check its health and as a guide to where fertiliser or lime may need to be applied. It may be possible to continue to monitor soil indicators cost-effectively using data collated from the analyses used by farmers. For example, NRM Laboratories analyse the properties of around 350 000 samples per year from individual agricultural fields at a total cost of around £3.5 million.
The soil samples in our study were submitted to NRM laboratories by both agronomists and farmers. Government-funded, national-scale soil surveys are carefully designed to ensure the results are representative, whilst farmers may focus their measurements on where they perceive a particular threat. To address the potential for bias in the farm data, we will compare estimates of mean values of our soil indicators by land cover type with those presented from other surveys, including Countryside Survey and the EU-wide LUCAS soil survey. By doing so we will be able to assess whether the estimates from farmers' analyses are sufficiently robust for soil monitoring. Similar approaches have been applied in France.
The soil indicators we have chosen to focus on are:
We focus on these indicators for two types of agricultural soils; arable plus horticultural, and grassland. The commercial data span over 12 years and we will compare the indicators over two periods; 2004–2009 and 2010–2015.
In addition to monitoring a range of soil properties, the farmers' analyses represent sites from all across England and Wales and, using the locations of these samples, we can generate maps of soil properties, such as these pH maps.
Maps of three other topsoil indicators (Olsen P, available K and available Mg) are also available in the form of pdf files for England and Wales. The concentration of these soil indicators is reported in units of mg kg-1 shown on the right hand side of the scale bar, and their index values according to the MAFF RB209 report are on the left side of the scale.
This research is funded through a NERC innovation internship grant reference number NE/N012380/1.
For more information contact Barry Rawlins.