Managing our soils: knowing and believing

In this special World Soil Day 2017 piece, Matt Aitkenhead and Cathy Hawes explore the ways in which soil is vital to our survival and discuss research looking at the relationships between carbon, climate change and land management.

Matt Aitkenhead & Cathy Hawes

Soil is vital to our survival. We need it to grow our crops, feed our livestock, maintain our water supply and provide a home for biodiversity. However, because we do not see it doing these things, we forget what it does and take it for granted. Like rain and sunshine, the soil has always been there, and we assume that it will always be.

This assumption is wrong. An area the size of Dunfermline is built over every year in Scotland, usually on the best, most fertile and cultivable soils. As well as this loss, erosion and compaction turn what is left of our best soils unworkable, and cause losses in soil nutrient content and fertility. When treated well, soil continues to be fertile and is more likely to stay that way in the future.

So how do farmers know how to take care of their soils? A lot of it is experience gained from years of working the land. Some of the knowledge comes in the form of advice from other farmers, and some comes from agronomists and scientists who create new knowledge about soil or new ways to work the land. Implementing the knowledge we need for sustainable land use and soil management is vital, and our understanding is constantly improving.

Land managers need to know that they can trust the advice they are given. Why risk changing your land management if there’s a chance this advice is wrong, or could cause a massive problem? Or, what if a new approach costs more and doesn’t make any difference?

This concept of trusting the science is important. Is the trust based on knowledge, or is it more like faith? Having confidence in a new management option is a combination of both, but really a farmer is choosing to believe in the person giving them advice. And if you don’t like the advice, then are you less likely to believe in it? What if believing in the science is inconvenient? This might seem like an odd question to ask, but just look at how many people choose not to believe in climate change, despite overwhelming evidence.

Soil carbon lies at the core of soil health and fertility, and is key to climate change mitigation efforts. The ‘4 per 1000’ (4 per mil) initiative aims to satisfy two goals at once, moving carbon from the atmosphere to the soil and thereby improving the soil and cutting greenhouse gas concentrations. The aim is to increase carbon stored in the soil by 0.4% per year. To do this would require significant changes to soil management.

The feasibility of achieving this ‘4 per mil’ has been argued against, and discussions are ongoing in London, Brussels and elsewhere to identify soil management options that enable soils to stay healthy and productive, and to look at ways of getting this information to the people who manage the soil.

The second goal is just as important, and in many ways, is harder to achieve.If a management option ensures that your soil will stay productive forever but reduces the amount you will earn for the next few years, would you choose it? If not, then what incentives would change your mind? It is not an easy question to answer.

Identifying the options that provide the best balance of sustainable soil management and farm income is a big research area. The only real way to do this is to try different types of management for several years, to get reliable data on the effects they have. Several UK research organisations have these long-term experiments, including Rothamsted Research, the Centre for Ecology and Hydrology, Cranfield University, Scotland’s Rural College and the James Hutton Institute.

Our Centre for Sustainable Cropping explores the long-term effect of an integrated management system on the whole arable ecosystem, including a range of indicators of soil health. The integrated system includes conservation tillage, cover cropping and carbon additions to the soil in the form of municipal green waste compost and straw.

We are monitoring how this affects the soil physical properties which determine how well plant roots can grow through the soil, as well as the availability of plant nutrients and the activity of organisms like earthworms and microbes that help with decomposition and carbon and nutrient cycling. Over time, we hope that improved soil health will allow us to reduce the amount of agrochemicals that are needed to produce good quality food.

At the James Hutton Institute, we are working on several other projects looking at the relationships between soil carbon, climate change and land management. The ClimateXChange work on peatland restoration aims to identify ways to stop carbon loss from drained peatlands, and to make these soils capture more than they release. We are also looking at ways to reduce compaction and erosion on agricultural land, and natural flood management methods that could also increase soil carbon.

Whatever results or recommendations we come up with, farmers need to be able to trust that these actions will work. In other words, they need to have faith in the research. And science isn’t perfect, making decisions based on research results always carries the risk that something has been missed or overlooked. When the first nuclear device was tested, Edward Teller (the father of the hydrogen bomb) thought there was a chance that the test would ignite the entire atmosphere and kill everything on Earth. They did it anyway.

It’s an uncomfortable truth that most science isn’t fact. It isn’t set in stone, but is based on a limited number of observations that are used to estimate how the broader system works. Even so, soil and agricultural research does give us important information about what will work and what won’t, and about what methods will make our soils more resilient.

But don’t just take our word for it. Come and see for yourselves. Visit us at the James Hutton Institute’s Aberdeen and Invergowrie sites, send an email or just phone us up. Come and see the evidence for what we know, and how we can help you.