UEA scientists working to reduce greenhouse gas emissions from farmland soil
Norwich-based scientists are playing a key role in an international partnership to reduce the farmland emissions of nitrous oxide – a greenhouse gas 300 times more potent than carbon dioxide.
Farmland soils are coming under increasing scrutiny as growers examine structure, organic matter, mineral levels and micro-organisms to boost crop yields and prevent nutrient loss.
But now Norfolk scientists hope to put another variable at the top of agriculture’s agenda – a damaging greenhouse gas whose expanding influence on our atmosphere has been attributed largely to emissions from agriculture.
The Nitrous Oxide Research Alliance (NORA) was formed in 2013 to explore how nitrous oxide (N2O) is produced by soil bacteria after the application of nitrogen-based fertilisers, and find ways to reduce its effects.
The University of East Anglia is one of the international partners in the EU-funded project which has already gleaned new insights into the importance of factors such as pH, copper and oxygen levels.
It is also working with fertiliser companies and waste management firms to find a commercially-viable means of reversing a century of increasing emissions of N2O– a greenhouse gas thought to be 300 times more potent than carbon dioxide, with an estimated 10pc contribution to global warming.
UEA vice chancellor Prof David Richardson, a microbiologist who is also this year’s president of the Royal Norfolk Agricultural Association, said: “Over the last 100 or so years, the levels of N2O in the atmosphere have increased by about 25pc, and they are still increasing. That is largely linked to agricultural activity. The increase in the planet’s population and the need for more productive farming has increased the use of fertilisers right across the planet.
The bacteria in the soils are very important because they add to the health of the soil, but equally they can take the nitrate that has been added and convert it into N2O.
“Some bacteria can destroy N2O and convert it back to nitrogen gas, which is inert. So if one has a better understanding of what conditions leave soils through their bacteria to be net producers of N2O and what conditions make them net consumers of N2O, then you might be able to lessen the impact of land management on the emission of this greenhouse gas, and turn around that 25pc increase in emissions that we have seen over the last 100 years.
“I want to be very clear that I am not against fertilisers. I believe it is better for the planet to make land as productive as we can.
“So I believe that we need to fertilise and replenish our land, so it is all the more important that in researching the production and consumption of this gas that we also work with fertiliser companies in this consortium.”
Prof Richardson said there have been two important breakthroughs so far: Copper has been found to be a key mineral in activating one of the enzymes that destroys N2O, while the acidity of the soil also plays a major role.
Prof Richardson said: “Copper is very important, and we know around 40pc of European agricultural soils are deficient in copper. And we find that soils at lower pH tend to emit N2O, while soils at a higher pH will not.
“If you take these two parameters together, the first thing might be to lime the soil and keep the pH high, and we might need to do a copper supplementation. Working with fertiliser companies might help us understand what kind of fertiliser regimes we could recommend for certain situations. And working with farmers, they might have measured the pH but have they measured their N2O emissions or the copper in the soil?”
From the lab to the field
One researcher working on the NORA project is Manuel Soriano Laguna, a third-year PhD biochemsitry student, originally from Linares in Andalucia, who came to work in Norwich mainly because of the city’s international reputation for biology and crop sciences among his tutors in Spain.
He is conducting laboratory experiments aiming to replicate oxygen-deprived waterlogged soils, or in a cold store to see how important proteins react in lower temperatures.
The focus of much of his work is an enzyme called N2O reductase, which breaks down nitrous oxide and turns it into inert nitrogen.
“This is the protein responsible for destroying nitrogen,” he said. “It is only present in soil microbes and bacteria. So if we want to find ways to reduce N2O emissions we have to focus on soil microbes.
“In order to work, this protein needs copper. If there is not enough copper in the soil, this protein will be switched off. Instead it will produce “copper chaperones”, and I am trying to find out what these do.
“The end result of the research will be to find ways of applying all this information into reducing emissions from soil. Can we use some soil organisms as N2O sinks, or can we modify fertiliser to put the right conditions in the soil so less N2O is being emitted? Hopefully we can find a way to continue with our agriculture but without unbalancing the nitrogen cycle, which is what is happening at the moment.”
The 31-year-old scientist was at this year’s Royal Norfolk Show to explain some of his findings, but said there was little awareness of nitrous oxide among the farmers he spoke to.
“I don’t think they know that much about nitrous oxide,” he said. “But Norfolk is quite a hotspot, because there is a lot of agriculture here, so there is a lot of N2O being produced.”
About Nitrous Oxide
While debates on greenhouse gases tend to focus on carbon dioxide and methane, nitrous oxide (N2O) has become an increasing concern, now thought to be responsible for 10pc of global warming.
The chemical perhaps best known as the dental anaesthetic “laughing gas” was first discovered by the British chemist Joseph Priestley in the 18th century when its atmospheric levels had been steady for millennia.
The subsequent rise in those levels in the last 100 years has been linked to the intensive use of fertiliser to increase farmland productivity in the 20th century.
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