Abstract: During the two 2019–2020 and 2020–2021 winters, field experiments with different thicknesses of buried soil for cold prevention were carried out in the vineyard at the eastern foot of Helan Mountain region. Combined with the monitoring results of soil temperature at different depths during the overwintering period, changes in root-zone soil temperature in the buried soil area of the vineyard were analyzed in this study. Understanding the effects of different thicknesses of buried soil on soil temperature could help the local grape community to assess freezing injury and manage buried soil during the overwintering period. The results showed that: (1) during the overwintering period of wine grapes, the soil temperature firstly decreased and then increased, and increased with the increase of soil depth, but the fluctuation decreased with the increase of soil depth. As the thickness of buried soil for cold prevention increased, the fluctuation of soil temperature was reduced. (2) The daily minimum soil temperature increased with the thickness of buried soil increased. Compared with no-buried soil (H0), buried soil that is 60cm thick (H60) improved the winter soil temperature at the depths of 20 cm and 40 cm by 0.2–2.7℃ (with an average of 1.1℃) and 0.1–1.3℃ (with an average of 0.6℃), respectively. (3) As the thickness of buried soil increased, at the three depths of 0cm, 20cm, and 40cm, the diurnal soil temperature range showed a decrease and the occurrence of the lowest soil temperature showed a time lag. By contrast, soil temperature at the depth of 60 cm was close to being constant. (4) Soil temperature was significantly (P<0.05) higher at the taproot zone (C0) than at the root zones that are 50cm, 100cm, and 150cm away from the taproot (C50, C100, and C150). The further away from the taproot, the lower the soil temperature was. On days when soil temperature was the lowest during the overwintering period, for the three treatments of 30 cm, 40 cm, and 50 cm thick buried soil, soil temperature at the depth of 20cm at C0 was 1.7–2.2℃, 1.7–3.3℃, and 2.4–3.4℃ higher than at the root zones of C50, C100, and C150, respectively. Overall, the risk of root being damaged by freezing decreased with the increase of soil depth. Thicker buried soil could improve the soil temperature by more and hence reduce the fluctuations of soil temperature. As the thickness of buried soil increased, the occurrence of the lowest soil temperature was delayed during the overwintering period. The chance of winter freezing injury occurrence was reduced with the increase of the thickness of buried soil; the winter freezing injury was more likely to affect the secondary roots than the taproot.

Key words: Soil temperature, Wine grapes, Thickness of buried soil for cold prevention, Freezing injury, Effects