The success of winter crops largely depends on how well they endure the winter. Factors such as the lack of insulating snow cover, alternating freeze-thaw cycles, unfrozen soil, and excess water beneath snow all pose challenges for winter crops. Fortunately, Paul-Tech’s soil station enables farmers to monitor these conditions effectively.
Using data from Farmer Tõnis’s Murumäe winter wheat field, Paul-Tech’s soil station reveals the insights into this season’s winter conditions. The first sharp drop in soil temperature was recorded on 4 December, when freezing weather hit without a thick snow layer to insulate the ground. The station measured an air temperature low of -10.8°C above the crop canopy that day.
Soil freezing is well illustrated by electrical conductivity, which is significantly affected by ice formation. The freezing process peaked on 13–14 December, as conductivity (j) dropped considerably, indicating that the freeze had reached 8 cm deep. Subsequent air temperature fluctuations between freezing and thawing, combined with heat stored in the soil, caused the frozen layer to retreat.
A warm spell starting on 19 December melted the soil completely by Christmas. While the return of sub-zero temperatures around New Year’s Eve refroze the topsoil, the effect was mild. Snowfall since then has acted as a strong insulator, keeping the ground soft. Low air temperatures on 4 and 6 January (-13.2°C and -12.3°C) had no impact on the soil, which remained under a protective layer of fluffy snow.
During winter freeze-thaw cycles, soil temperature is buffered around 0°C due to the high water content in the soil and the high value of latent heat capacity of water freezing. The best indicator of whether the soil is frozen or thawed is its electrical conductivity (j). Fully frozen soil shows a conductivity range of 0–5 µS/cm, while partial drops in conductivity can reveal the depth of the frozen layer at any given moment.