Soil is often out of sight, out of mind for many of us, but it is critically important for our ability to grow food and protect water supplies. Despite its significance, we know very little about how the changing winter climate could be affecting one of our most important resources — the health of our soils. The trend towards warmer winters is leading to a greater frequency of freeze-thaw events that deplete the insulating snowpack, creating colder soils. This alters not only the physical but also the chemical and biological properties of soils — a piece of the biogeochemical puzzle that until now has largely been ignored. These factors subsequently change the movement of water, carbon and nutrients in soils during the winter. The Ecohydrology Research Group at the University of Waterloo is conducting research at rare to discover how soils are changing and what that means for the health of agricultural soils and water quality.
Many scientists have traditionally thought that frozen soils are dormant, but our studies show that soils remain biogeochemically active during winter months, undergoing different processes than in other seasons. We are finding that this can affect the water quality of streams during spring snowmelt. Among other implications, increased nutrient loading from soil to water bodies can cause algal blooms — a rapid growth of algae that can deplete the water’s oxygen and produce harmful toxins. That is why our researchers are working to understand how different potential climatic scenarios could alter the movement of carbon and nutrients in soils and water. The goal is to predict the impact of changing belowground temperatures and snow cover on biogeochemical processes in soils during the winter.
Implications for Soil Health
Identifying biogeochemical drivers such as energy and nutrient delivery on winter microbial community composition, functions and dynamics is critical to establishing a mechanistic understanding of winter biogeochemical cycles. This research could also affect the health of soils and their ability to support plant growth. The interdisciplinary work on winter soil processes, led by the Ecohydrology Research team, examines microbial activities during winter conditions, to estimate repeated freeze-thaw cycles’ effects on microbial resilience and the biological carbon and nutrient release.
Led by Professor Fereidoun Rezanezhad and funded by Global Water Futures, the Winter Soil Processes project aims to develop novel experimental systems that simulate realistic soil conditions during freeze-thaw cycles, while improving the fundamental understanding of biogeochemical processes under freeze-thaw events during the winter-to-spring transition.
Learn more about Winter Soil Processes and the Global Water Futures project at the University of Waterloo.
By Dr. Fereidoun Rezanezhad, Assistant Professor in the Department of Earth and Environmental Sciences, University of Waterloo
Cover photo courtesy of Tatjana Milojevic.