_:b1216769 . _:b1216769 "A zone beneath the land surface and above the level of permanent groundwater or phreatic zone in which water has a hydraulic head less than atmospheric pressure and is retained by a combination of adhesion and capillary action."^^ . _:b1216769 . _:b1216769 . _:b1216769 "Wikipedia:Vadose_zone"^^ . _:b1216769 "web:http://wasg.iinet.net.au/terminol.html"^^ .