Abstract
Timing subsurface drainage (SD) at two critical periods to coincide with melting of frozen soil water and the rainy season may effectively lower the groundwater table and increase the leaching of salts. A field experiment was set up in the eastern coastal saline area of Hebei Province, China, to assess the effects of SD on soil water and salinity. Subsurface drainage significantly prevented the rise of the groundwater table during melting of frozen soil water, and thus considerably reduced salinity across soil layers, especially in the 30 cm layer. In the rainy season, the SD effectively held the water depth to within 1 m, preventing waterlogging by more than two‐thirds and more than doubling the leaching of salts from the soil surface. The contents of Na + , Mg 2+ , Cl − and SO 4 2− under SD reduced substantially (7.1–18.8%) after rainfall events and the mobility of ions was in the order Na + > Cl − > SO 4 2− > Mg 2+ . For the remaining period of the year when subsurface drainage was not carried out, the soil salinity generally increased but the salinity and groundwater table in areas under SD were slightly lower than those in the control area. Copyright © 2016 John Wiley & Sons, Ltd.