Effects of freeze-thawing processes on soil water transport in degraded
Seasonal freeze-thawing affects soil water migration and distribution,
especially in semi-arid degraded agricultural areas, with important
impacts on crop production, and wind erosion. We assessed the
distribution and migration of soil water in degraded agricultural areas
during freeze-thawing and the effect on plant growth and wind erosion.
Soil water content (SWC) and soil temperature (ST) dynamic
characteristics at a depth of 0-2 m in the semi-arid agro-pastoral
northern China are discussed, using data from November 2018 to May 2019.
Changes in water potential energy and pore pressure gradient caused soil
water migration to the upper layer, which led to a slight decrease in
SWC at each layer before ST dropped to the freezing point. The vertical
migration distance of soil water exceeded 70 cm, and the SWC above a
depth of 100 cm increased significantly during thawing; the water was
mainly obtained from the soil layer below a depth of 120 cm. The initial
SWC is the main factor affecting the freeze-thawing process. Our results
can partly explain the occurrence of wind erosion in spring and provide
a scientific basis for predicting soil water status and developing
irrigation and erosion control strategies.