<rleton students who try their best to remain inside during the winter months would be hard pressed not to have noticed the tremendous amount of snowmelt in the past week. Muddy conditions and small ponds on walkways throughout Northfield have put all of us at risk of getting a little wet, but this concern seems petty in comparison to the bigger implications of this early thaw.
In some ways the thaw is good. Some plants actually need to experience freeze thaw cycles in order to proliferate. If the seed of a plant is very tough, one way to break it open is from water infiltrating cracks and then freezing. The expansion of water when it freezes can help weaken the shell. However, another effect of freeze-thaw cycles is to damage the tiny absorbing roots of trees. This root damage results in less nutrient uptake, and therefore more nutrients getting washed downstream.
In general, the freeze-free growing season has increased 16 days in the last 60 years. Overall, however, the slightly increased crop yields aren’t worth the almost 60% increase in heavy precipitation events for Minnesota farmers. These precipitation events increase the amount of retention ponds farmers must dig in their desperate attempt to keep from losing more topsoil and nutrients to the rain. They also may increase the amount of tiling on their fields in an attempt to keep water from pooling on them, causing agricultural runoff to directly enter our rivers.
This thaw shouldn’t have any immediate, adverse effects to the Arboretum, as freeze thaw cycles are both natural and important. The increased nutrient runoff come springtime, however, is a tremendous concern for communities downstream.