The findings of an international research project involving Plant & Food Research suggest that soils have a “memory”, which can directly impact how they store c s and the role they may play in mitigating climate change.
The Earth’s soils contain more carbon than all of the carbon held in plants and the atmosphere combined. Plants roots are an important source of the carbon stored in soils. Much of that carbon is stored in the topsoil, where the plant roots are concentrated, while subsoils tend to be depleted and have the potential to store more carbon.
One solution to increasing soil carbon storage may be to grow deeper rooting plants that deposit more carbon in the subsoil. But research from a team of international scientists published in the leading journal Nature Geoscience has shown that the addition of new plant carbon to low carbon subsoils can actually stimulate the loss of existing carbon.
In contrast, the loss of existing carbon from high carbon topsoils was much lower. In essence, the study found that soils have a “memory” that reflects their conditioning to low or high carbon input environments.
Importantly, the research team also found evidence that subsoils gradually adapt to higher carbon inputs over time, increasing their potential to store carbon from deeper rooting plants.
Dr Mike Beare from Plant & Food Research is a co-author of the paper Soil carbon losses due to priming moderated by adaptation and legacy effects, alongside collaborators from the University of Zurich in Switzerland, the Thünen Institute of Climate‐Smart Agriculture in Germany and PSL Research University in France. The soils were collected from a unique set of sites on the West Coast of New Zealand’s South Island where carbon-rich soil has been buried for different periods of time.
Although much of the experimental work was conducted in Switzerland, the team worked closely together to design, analyse and interpret the findings reported in the paper.
“Storing more carbon in subsoils would help to reduce the amount of carbon in the atmosphere, which is essential for climate change mitigation,” says Dr Beare.
The research also found when carbon-rich topsoils are cut-off from regular inputs of plant carbon, they gradually lose soil carbon and become more susceptible to loss of their existing carbon. This may occur when topsoils are left fallow for extended periods and highlights the importance of maintaining plant cover.
Although the losses of existing carbon are important, the team also found that the addition of new plant carbon never resulted in a net loss of total carbon. In most of the soils tested, the addition of root-derived carbon resulted in significant carbon gain.
“This international project is important as it’s another step forward in understanding what influences carbon storage in soils, so we can create climate change mitigation strategies that work within the limits of the natural environment.”
This work was funded by the Swiss National Science Foundation and by the European Union’s Horizon 2020 research and innovation programme.
Additional support was provided by Plant & Food Research internal investment through the Ministry for Business, Innovation and Employment’s Strategic Science Investment Fund.
Source: Plant & Food Research