Ice crystals formed on the outside of a soil sample taken from Alaska’s permafrost. Credit: Erin Rooney IG: @soil_roonster

January 15, 2019 – Winter soil freezes, heaves, and moves! The Soil Science Society of America (SSSA) Jan. 15 Soils Matter blog looks at the freeze-thaw cycle, how it changes soil on a microscopic level, and the reaction of Alaska’s unique permafrost soils.

“Freezing deforms the soil,” writes blogger Erin Rooney. “Frost heaving allows mineral subsurface layers–or horizons–to be squeezed up through the soil. This moves horizons from lower to higher. This feature is known as a ‘mud boil’ or ‘frost boil.’” Rooney is a graduate fellow at Oregon State University.

But the icy drama doesn’t stop with what human eyes can see. The cracks, freezing, and expansion can occur on a tiny scale as well. This can release minerals and further change the soil’s composition.

In the case of Alaska’s permafrost soils, the changes may keep coming. “These soils have stored an estimated 40% of Earth’s terrestrial organic carbon for centuries. The soil’s ability to continue storing carbon belowground will depend on soil resilience to changes in the climate. These changes include increasing variability in winter air temperature and the resulting increase in freeze-thaw cycles.”

To read the entire blog post, visit

The Soil Science Society of American (SSSA) is a progressive, international scientific society that fosters the transfer of knowledge and practices to sustain global soils. Based in Madison, WI, SSSA is the professional home for 6,000+ members dedicated to advancing the field of soil science. It provides information about soils in relation to crop production, environmental quality, ecosystem sustainability, bioremediation, waste management, recycling, and wise land use.

SSSA supports its members by providing quality research-based publications, educational programs, certifications, and science policy initiatives via a Washington, DC, office. Founded in 1936, SSSA proudly celebrated its 75th Anniversary in 2011.