ECT Fringe Event WCSS22

ECT trustee Jonathan Silvertown writes about the key take-home messages from our fringe event at the World Congress of Soil Science 2022 held on 4 August in Glasgow.

Anyone who attended Richard Bardgett’s recent ECT Webinar on the Colt Park LTE will know that long-term experiments need soil science and vice versa. For one thing, soil processes are often slow and require years of study before they reveal themselves. So, the ECT seized the opportunity to run a fringe symposium on LTEs at the 22nd World Soil Congress in Glasgow, hosted by the British Society of Soil Science in August. Our symposium showcased five long-term experiments on the ECT national register. Raj Whitlock from Liverpool University talked about the Buxton Climate Change Impacts Laboratory, Ruth Mitchell from the James Hutton Institute spoke about the woodland colonisation experiment MOORCO. ECT Chair Jerry Tallowin presented the North Wyke Farm Platform experiment. Shangshi Liu (University of Manchester) talked about the grassland restoration experiment Colt Park Meadows, and Bid Webb finished off the talks in the morning talking about the BangorDIVERSE experiment taking place in Wales.

In the afternoon, talks were focused on soil health policy in relation to climate change (Mike Morecroft, Natural England) and food security (Christine Watson, Scotland’s Rural College). The day finished with a round-table discussion in which we shared the key take-home messages summarised here.

What LTEs tell us

 1) Planting trees on organic-rich soils (>25% organic matter) can actually emit more carbon than it sequesters. The increase in carbon being stored above ground does not compensate for the loss that occurs below ground. Because of this, Ruth Mitchell highlighted that planting more trees in such soils to sequester carbon can be counter-productive.

2) Crops and trees need to be planted on the right soil type was the take-home message of Christine Watson’s presentation. Many mistakes have been made by planting on unsuitable soils, which is detrimental to yields.

3) Soil is lost at a faster rate than it is formed, as illustrated by flumes like this one at the North Wyke long-term experiment.

4) Soils contain the largest carbon store in the terrestrial biosphere, even outstripping the amount stored in fossil fuel deposits. In which context Mike Morecroft (Natural England) spoke about the importance of soil health to climate change mitigation.

5) Interactions between tree species affect ecosystem services. Bid Webb talked about the BangorDIVERSE experiment and its origins. This experiment began as a Free Air CO₂ Enrichment (FACE) climate change experiment.

6) Researchers often find new uses for existing experiments; a point that was made in Shangshi Liu’s talk on Colt Park Meadows which illustrated the cumulative value of LTEs.

7) Different processes occur at different rates. Raj Whitlock described the sequence in which different processes have emerged since the Buxton Climate Change Laboratory’s climate change experiment was established in 1993.

8) Plot experiments sample their enfolding landscapes. Christine Watson illustrated this with a talk on soil health and food security policy. Small-scale experiments can be used to understand the whole landscape if they manipulate wider management practices. A good example of this is North Wyke where grazing system changes have been replicated at a larger scale.