Tuesday, April 11, 2017

Thawing crops worldwide creating greenhouse gas emissions, says Canadian study

Crops thawing from snow and ice are creating greenhouse gas emissions, says a study by researchers from Canada's University of Guelph and University of Manitoba published in Nature Geoscience. Researchers say the first of its kind study "reveals that worldwide emissions of nitrous oxide (N2O) from agriculture are underestimated by as much as 28 percent," Deirdre Healey reports for the University of Guelph.

The study monitored emissions over 14 years at sites in Ontario, nine years at sites in Manitoba, and included emissions data from 11 cold climate sites around the globe, Healey writes. Claudia Wagner-Riddle, the study’s lead author, told Healey, “Up until this point, no one has accurately calculated just how much nitrous oxide is released from the thawing of cropland. Our study shows that a big chunk of agricultural emissions is not being considered, making it even more urgent that we find a way to manage and reduce these emissions.”

Healey writes, "In the Northern Hemisphere, annual freezing affects areas of intensive corn, wheat and soybean production in the U.S., Canada, China and Northern Europe. Cropland is a major source of N2O because inorganic fertilizer, manure and legumes provide nutrients for N2O production by soil microorganisms." Wagner-Riddle told her, “When the soil thaw`s, the nutrients that were sitting dormant are released so there is an increase in microbial activity, which results in the production of nitrous oxide."
Daily N20 fluctuations at two study sites. Red is mean maximum air temperature, gray is snow depth, blue soil temperature at 5 cm and black is soil liquid content.

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