Effects of Irrigation at Different Times During the Freeze--thaw Period
on Soil Evaporation
Abstract
Controlling soil evaporation during the seasonal freeze–thaw period has
important practical significance for alleviating the water shortage in
northern China. To investigate the influence of different irrigation
times on soil evaporation during the freeze–thaw period, a series of
field soil evaporation experiments of bare soil and sand mulch
treatments with six different irrigation times were conducted. Soil
evaporation characteristics during the three freeze–thaw stage were
determined, and the major factors influencing soil evaporation were
analyzed using the Random Forest model. The results showed that the
cumulative soil evaporation of bare soil irrigated at different times
during the freeze–thaw period was 43.1–50.37 mm, which was
33.8%–56.4% higher than that of bare soil without irrigation, and
soil evaporation decreased by 10.4%–39.2% after the addition of
mulched sand. Shortly after irrigation, surface sand mulch exhibited a
weak inhibitory effect on soil evaporation in the stable freezing stage
and later thawing stage. Sand mulch with irrigation in the early
unstable freezing stage had the most positive effect on soil moisture
preservation, with 80.95% of the irrigation water stored in the soil
during the freeze–thaw period. Simultaneously, the surface soil
moisture content was the major factor affecting evaporation in irrigated
treatments in the unstable freezing stage and stable freezing stage;
surface soil temperature, surface soil moisture content, and average air
temperature were the major factors affecting soil evaporation, and
surface soil moisture content had the greatest contribution to soil
evaporation in the thawing stage. The results suggest that the addition
of irrigation water early in the winter along with sand mulch in
agricultural fields may be a beneficial practice to reduce water stress
in arid and semi-arid areas.