Buried Reed Barrier Layers for Sustainable Desalination of Coastal Saline Soils

Soil salinization poses severe threats to agricultural production and ecological sustainability in the Yellow River Delta of China. Conventional porous barrier materials such as straw, river sand and construction waste have unavoidable limitations in raw-material supply and environmental safety. This study explored the potential of Phragmites australis segments as an eco-friendly, locally available porous barrier layer for sustainable coastal saline-soil remediation. Laboratory soil column simulation tests were carried out with four reed-segment length treatments (2 cm, 5 cm, 8 cm, 11 cm) and a reed-free control (CK) to investigate soil percolation and drainage, vertical salt content distribution and layered desalination rate. Buried reed segments significantly enhanced percolation and drainage under leaching, with the 5 cm treatment performing best. After leaching, soil salt content increased monotonically with depth in all treatments, and CK retained significantly higher salt contents than the reed-amended treatments throughout the profile. Reed-segment length exerted slight effects on topsoil desalination but significant effects on deep soil layers. All reed treatments achieved higher desalination rates than CK. The 5 cm treatment yielded stable salt-mass-weighted profile desalination rates of 96.59%, 96.76% and 97.15% at 24 h, 84 h and 168 h, respectively, showing optimal performance under laboratory soil-column conditions. These findings provide a sustainable, low-cost technical reference for the ecological amelioration of coastal saline soils.