Hidden N2O Emissions Found In Frozen Soils

A recently published study is suggesting that emissions of nitrous oxide (N20) from frozen soils may be significantly higher than once thought. In fact, emissions may be about 17 to 28 per cent greater for cultivated soils frozen in winter.

The study, published by the University of Manitoba and the University of Guelph, argues that current calculations do not account for freeze-thaw emissions.

Dr. Mario Tenuta, professor in applied soil ecology at the University of Manitoba, explains what may be causing the emissions.

"What we're finding through our research is that it's actually produced during the thaw, by a process called denitrification, and that's a process where nitrate that would be left over from the cropping year before, and gets reduced or used by bacteria...and it emits nitrous oxide."

Tenuta says N2O is 300 times more potent than CO2, adding cropland soils are by far the largest source of nitrous oxide.

“We hope revision to the estimate of N2O emissions from seasonally frozen cultivated soils will encourage research and use of cropping practices to lower greenhouse gases from agriculture,” he commented.

The study was published this week in Nature Geoscience.