_:b1217733 "FAO:http://fao.org/ag/agl/agll/wrb/doc/wrb2006final.pdf"^^ . _:b1217733 . _:b1217733 . _:b1217733 . _:b1217733 "Planosols are soils with a light-coloured, surface horizon that shows signs of periodic water stagnation and abruptly overlies a dense, slowly permeable subsoil with significantly more clay than the surface horizon."^^ .