A common fermented feed for livestock provides a powerful greenhouse gasbut scientists in Kansas say they’ve figured out an affordable way to tackle the problem someday.
A team of scientists from Kansas State University has published the best estimate yet of the amount of nitrous oxide released into the atmosphere silagewhich they suggest could be the third largest source of gas in the country.
Now they want to get the attention of federal regulators and the agricultural industry to address the problem.
“So we can do something to minimize it,” said associate professor of civil engineering Jeongdae Im. “Luckily we have a simple solution.”
Cheap solution for a big problem
The new research suggests that silage can produce 30 times as much nitrous oxide as another common practice, which involves burning corn stubble and other crop residues after harvest. But this is despite the fact that the American Environmental Protection Agency regularly provides input field fires in its emissions reportsthe impact of silage is being overlooked, K-State scientists say.
The solution proposed by the scientists involves an inoculation agent. Treating 1 ton of silage would cost 4 cents, K-State researchers concluded.
I’m saying that $5 million could process all the silage produced in the US each year.
“It’s really exciting,” Im said. “We can reduce 2% of total nitrogen oxide emissions (in the US).”
I, who is also an environmental microbiologist, won one of the The National Science Foundation’s Most Coveted Awards to conduct this research.
The K-State team’s findings appear in last month’s issue of the National Academy of Sciences’ PNAS nexus magazine.
Retain heat and deplete the ozone layer
The Intergovernmental Panel on Climate Change says that Earth’s atmosphere now contains 20% more nitrous oxide than before the Industrial Revolution.
Unlike the increase in carbon dioxide that comes mainly from fossil fuels, humans are adding nitrous oxide to the atmosphere largely through agriculture.
Although this gas accounts for only a small portion of global greenhouse gas emissions, its potential worries scientists. Compared to carbon dioxide, nitrous oxide is approximately 265 times more effective at retaining heat over a period of 100 years, according to an EPA report. It also puts the ozone layer which protects people and other life on the Earth’s surface from harmful solar radiation.
Im and his colleagues conducted laboratory experiments with different types of silage as a first, crucial step in finding out how much of the gas comes from that source.
Silage is chopped plant material – often corn, sorghum or alfalfa – that is fermented and stored in silos, bunkers and plastic-covered mounds across the country.
The team examined the bacteria that produce nitrous oxide and tested a variety of additives and inoculants to deal with it.
The bacteria produce nitrous oxide under stress, I said, when they don’t have access to enough carbon compounds. So the team found a combination of ingredients that kills the most bacteria and then reduces stress in the survivors. It gives the remaining microbes a boost of carbon compounds.
This two-pronged approach prevented 99% of nitrous oxide emissions in the scientists’ silage experiments.
Verifying the safety of the treatment
Scientists and policymakers use formulas to add up the numbers estimated toll that different types of emissions burden society, for example by damaging human health and property.
These formulas suggest that the nitrous oxide released from silage could cost U.S. society hundreds of millions of dollars annually, Im said.
However, several steps need to happen before it is likely that a solution of the type proposed by K-State civil engineers and agronomists could possibly gain widespread attention.
Researchers will conduct larger-scale studies to verify their findings.
They will also further investigate the extent to which chlorate, one of the ingredients in the treatment, remains in the pit after fermentation.
This is critical to verify the safety of the treatment.
“Anything that is toxic to microorganisms can be toxic to humans,” Im said. “One of the things we have to answer is the fate of this chlorate at the end of this silage process. And we are investigating it.”
But ultimately, I hope that carbon markets or other incentives can make treating silage to reduce emissions an attractive option for farmers.
Celia Llopis-Jepsen is the environmental reporter for the Kansas News Service.
This article originally appeared in Topeka Capital-Journal: Farms can reduce greenhouse gases from silage: Kansas research
