In the words of Franklin D Roosevelt, ‘A nation that destroys its soil destroys itself.’ Soils harbour a complex diversity of microbes that cycle atmospheric carbon and nutrients to support plant growth. Understanding how distinct microbial species in the soil interact with plants to regulate ecosystem health is critical to promoting sustainable soil management – a burgeoning facet of climate science.
A team of researchers led by Dan Buckley, professor of microbial ecology at Cornell University, has identified a new bacterial species that helps reveal how carbon is cycled through the soil. Using a technique called DNA-Stable Isotope Probing, the team visualised the compounds being broken down by soil bacteria. This revealed that specific aromatic compounds, essential for plant growth, were being degraded by an unknown bacterial species. The team cultivated and confirmed the new species, P. madseniana, which was named after the late Gene Madsen, an esteemed researcher of soil ecosystems.
Soil microbes convert atmospheric carbon into organic forms that are utilised by plants. They also degrade organic matter to liberate essential plant nutrients such as nitrogen and phosphorous. Due to the dependency of plants on these nutrients, Buckley thinks that trees release aromatic compounds that stimulate the growth of plant-promoting bacteria such as P. madseniana. ‘We think that the trees are promoting bacteria growth as a strategy to enhance decomposition. In this way the trees can better access nutrients locked in soil,’ says Buckley. By influencing the soil’s composition of carbon-cycling bacteria, plants may be able to alter the fate of atmospheric carbon.
The team are convinced that soil research has a major role to play in mitigating and adapting to climate change. ‘Soils have a powerful impact on our climate. Unfortunately, global models have a difficult time representing the soil carbon cycle because we still have much to learn about microbial processes,’ says Buckley. A deeper understanding of how bacteria regulate carbon cycling in soil ecosystems may allow researchers to better predict the effects of climate change on soil health.
‘Soils are the foundation for our lives. Since they’re just underfoot we often take them for granted, but we rely on them for nearly all of our food and for the many ecological services they provide,’ says Buckley. In a 2015 report titled Status of the World’s Soil Resouces, the Food and Agriculture Organization of the United Nations identified the ‘role of soil fauna in controlling carbon storage and cycling’ as a key knowledge gap to promoting sustainable soil management. Now in 2020, this discovery is the latest in the global scientific movement foregrounding soil research – an unsung hero in the fight against climate change.