Agricultural soils contribute to climate crisis by releasing nitrous oxide

A new study published in the journal Proceedings of the National Academy of Sciences has found that poorly drained agricultural soils produce nitrous oxide emissions in quantities large enough to contribute to climate change. According to the scientists, such negative effects far exceed the potential benefits of using these soils as carbon sinks.

Researchers, policymakers, and farmers have long explored the potential of agricultural soils to sequester carbon, and thus mitigate climate change. However, a research team led by Iowa State University has argued that such strategies should take into account the fact that such soils emit nitrous oxide, a gas that has 298 times the warming potential of carbon dioxide over 100 years.

As they cycle nitrogen, microorganisms in the soil emit nitrous oxide as a byproduct. Furthermore, since nitrogen stimulates nitrous oxide production, adding nitrogen fertilizers to the soil results in even more emissions. 

In order to gather data for the study, the researchers used small containers placed on various locations on top of corn and soybean fields in central Iowa that measured nitrous oxide emissions every four hours.

“In this study, we show that the climate warming effects of nitrous oxide emissions from local corn and soybean soils are two-fold greater than the climate cooling that might be achieved by increasing soil carbon storage with common agricultural practices,” said study senior author Steven Hall, an associate professor of Ecology, Evolution, and Organismal Biology at Iowa State University.

According to Professor Hall and his team, these findings suggest that management plans should also encourage nitrous oxide mitigation strategies together with carbon sequestration. Such strategies include more efficient uses of nitrogen fertilizers, the employment of new products such as enhanced efficiency fertilizers, or the application of biochar to agricultural fields.

“If we want to maximize our climate benefit, we want to be strategic about it. We’re not simply going to flip the switch on climate just by putting more carbon in the soil. Nitrous oxide emissions need to be a priority as well,” concluded Hall.

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By Andrei Ionescu, Earth.com Staff Writer