Shallow subsurface drainage in an irrigated vertisol with a perched water table

allium cepa anegamiento crop yield drainage souterrain drainage taupe drenaje topo engorgement du sol groundwater table gypse gypsum irrigation mole drainage nappe souterraine new south wales nueva gales del sur rendement des cultures rendimiento de cultivos riego salinidad salinity subsurface drainage vertisol vertisoles vertisols waterlogging yeso