Farm soils are much richer in micro-organisms than any other land type, researchers have found.
A quarter of all known species live in soils, including bacteria, fungi and worms, and this biodiversity is essential for numerous ecosystem services.
In a paper published today in Nature Communications, Bangor University PhD student Paul George revealed that no where is this hidden world more diverse than on farms.
The more intensively this land is fertilised, cropped and trampled, the greater the variety and abundance of microbes, he discovered.
Only soil invertebrates and other micro-animals failed to follow this trend.
“We don’t yet know exactly why this is,” he admitted.
“It could be due to agriculture being present on soil types which are more inherently suited to supporting a larger number of species.
“Or it could be the management practices we use in agriculture creates more varied habitats for different species to exploit.”
Paul, a Canadian with 18th century Welsh roots, is studying at Bangor’s School of Natural Sciences and the Centre for Ecology and Hydrology (CEH).
He analysed soil samples from 436 locations across seven different land types in Wales – a country considered ideal for the purpose due to its diverse landscapes and compact nature.
By using a process called molecular meta-barcoding, in which DNA “barcodes” are assigned to every organism found in a sample, he was able to identify no fewer than 100m soil creatures.
This included 29,690 types of bacteria and 7,582 types of fungi.
As well as identifying organisms currently in soil samples, the process can detect DNA fragments from absent species that were recently present.
Previously Paul has used the technique to go “pathogen prospecting” for potentially harmful microbial species.
“This branch of science is still developing and is being exploited to explore ‘hidden’ biodiversity in our seas and rivers – and even the human gut,” he said.
“Here we have applied it to our soil.
“The approach is highlighting the amazing diversity of species we previously couldn’t see – many species will not grow in laboratory situations using current methods.”
The research is considered important as soil condition is a global indicator for land degradation within the UN’s Sustainable Development Goals.
Wales is one of the few governments globally which protects soils at the highest level: it includes soil condition as one of its 46 National Indicators for sustainable development.
In turn this informs the delivery of the country’s Well-being of Future Generations Act 2015.
Prof Bridget Emmett of CEH said other countries should be following Wales’ lead.
“By including soils as a national indicator and tracking that change over time, Wales has emphasised how soil is critical to so many benefits we derive from our land,” she said.
Soil scientists now want to understand why soil organisms multiply in areas of low diversity above-ground.
In time this may enable them to develop ways of “encouraging” a wider species richness in different soils.
It will also improve understanding of how soil organisms influence eco-system services such as food production, flood mitigation and carbon storage.