The impacts of changes in snowfall on wintertime soil greenhouse gas emissions using an automated chamber system

Background/Question/Methods

With increasing global surface temperature, snow cover has decreased in many regions. Snow is an effective insulator, so reduced snow cover will enhance soil freezing and increase the depth of frost, and the frequency of freeze-thaw cycles is likely to increase due to reduction of snowpack thickness. Freeze thaw cycles can strongly impact soil C and N dynamics. We investigated the winter and spring response of soil greenhouse gas emissions (CO₂, CH₄ and N₂O) to changes of snow depth in a corn-soybean-wheat cropping system.

This study was established in 2010 at the Kellogg Biological Station (KBS) after wheat rotation prior to corn. The experiment is a completely randomized design (CRD) with three levels of snow depth: ambient, double snow depth, and no snow. Each level had four replicates. Twelve automated chambers were randomly assigned to treatments and greenhouse gas fluxes measured 4 times per day in each plot.

Results/Conclusions

There were more freeze-thaw cycles in the no snow treatment than in ambient and double snow treatments in both 2011 and 2012, though fewer in the warmer 2012 winter with less snow overall. Soils in the no snow treatment released more N₂O than did soils in the ambient and double snow treatments, soil but CH₄ fluxes were uniformly low with no significant difference across three treatments. CO₂ showed expected seasonal changes with the highest emission in spring and lowest emissions through the winter. N₂O peaks were higher in spring due to freeze thaw effects.