The effects of freeze-thaw process on soil water migration in dam and slope farmland on the Loess Plateau, China.

The seasonal freeze-thaw process affects soil water migration, which influence spring planting, especially in arid and semi-arid regions that cannot be irrigated on the Loess Plateau. This study was conducted to evaluate differences in the freeze-thaw process and water migration between dam farmland (DF) and slope farmland (SF). To accomplish this, two typical agricultural soils (DF and SF), soil water content (SWC) and soil temperature (ST) were monitored at different depths (15, 30, 60 and 90 cm), were investigated under freeze-thaw conditions from November 2015 to April 2016 in the Northwest China. The results showed that different freeze-thaw process between dam farmland (DF) and slope farmland (SF). The DF can keep soil water content resulting from longer frozen period. Thermal transmission between soil and air in SF is greater than that in DF. The SWC values in DF were higher than in SF at each depth layer under similar soil temperature. Migrated and incremental SWC in the DF is greater than that in SF during the freeze-thaw process. The initial SWC is the main impact on freeze-thaw process in this study. This research can provide useful information to guide the water management of seasonally frozen agricultural soil.