by Professor Colin Campbell, Chief Executive, James Hutton Institute

The excellent series of RSGS Climate Emergency Summits is focused on climate solutions, and our soil is certainly one of the most promising nature-based solutions available to us.

You may know how important soils are globally, and the threats to them from over-consumption and climate change. In Scotland we are more fortunate, but that doesn’t mean we can be complacent. Much of the focus on soils has been around how important they are as a store of carbon, and this is entirely true – the c3,000MT of carbon in Scottish soils is equivalent to 186 years of greenhouse gas emissions. There is a hierarchy of carbon stored in soils under different land covers, with the greatest amounts in peatlands, heath and moorland soils, followed by woodland and then grassland and arable. For peatlands there is a plan of action and resources are starting to be made for restoration, even if many would say we need faster progress to match the urgency of the situation. Similarly, for soils suitable for tree planting there are targets which will help sequester carbon and, if the right tree is planted in the right place, help restore biodiversity.

The focus of the Climate Emergency Summit on soil is agriculture, and here there is still untapped potential to store much more carbon. However, the direct and indirect benefits of having more carbon as organic matter in our managed agricultural soils are much wider than just storing carbon. This is because the organic matter in soil is the critical parameter affecting how soil functions in its many ways. It fuels the megadiversity of life in the soil, improves soil structure, and so stores more water and improves infiltration; it helps supply nutrients, buffer and degrade contaminants, and reduce the likelihood of erosion by wind and rain, and reduces the transfer of pollutants to our waters and food chain, and makes our land more resilient to droughts and floods. It simply couldn’t be more important. But do we have a plan to increase the soil organic matter? Not explicitly.

We are fortunate also in having high-quality scientific evidence and knowledge of our soils. Our National Soil Inventories have shown organic matter levels have remained relatively constant from the 1980s. At the time of the last survey in 2007 we were deeply concerned they were declining, so this was seen as good news. However, historically we have traded down the land high in organic matter to land low in organic matter, eg in clearing woodland, creating arable from grassland. We have therefore already made major withdrawals from the long-term Natural Capital Bank that is our soil, and our nature is less abundant and our soils less resilient. Consequently, we are in danger of sitting on our laurels again if we are happy we are no longer reducing soil organic matter and everything is ok. It isn’t. Climate change alone will put severe pressures on our soil, and we need it to be much more resilient than it is. We need a plan that grows our soil capital before we can safely withdraw more products and services.

Most farmers have an intuitive feel for what good soil is, and appreciate it is a living thing that needs nurture. Many are leading progressive change using agro-ecology and regenerative techniques. Consumers are also increasingly wanting to know we haven’t damaged Nature or accelerated climate change, so there is a big commercial driver for the supply chain to move quickly in a more sustainable direction. We also have some progressive policies on land use and climate change; but is something missing in the round if things are not really changing? What we need then are ways to bring this together in a common vision of what will make our soils more vibrant with life-supporting nature; growing healthy food and useful materials without adding to the greenhouse gas emissions or diminishing the quality of our air and water. A National Soil Action Plan with targets for increasing our soil organic matter and growing our soils resilience could be one way forward. While there are international precedents arising from the COP Paris Treaty in the quatre per mille initiative, there need to be local ways of achieving the same thing that account for local differences in soil resource.