Abstract
Soil salinisation and freshwater scarcity severely restrict global agricultural sustainability. A laboratory soil column experiment was conducted to ameliorate extremely heavy saline soil using high‐salinity brackish water drip irrigation. The initial soil had a saturated paste extract electrical conductivity (EC e ) of 109.5 dS·m −1 , a sodium adsorption ratio (SAR) of 89.23 (mmol·L −1 ) 0.5 and a pH of 7.70. Five irrigation water salinity levels (0.45–34.0 dS·m −1 ) and three irrigation scenarios were designed: 254 mm single leaching (S), 500 mm single leaching (SS) and alternate brackish–freshwater leaching (254 + 246 mm, SF). Results showed that S desalinated the 0–40 cm layer by 61%–81%, while SS and SF achieved 0–70 cm desalination with 0–40 cm rates of 75%–93% and 78%–93%, and reduced 0–90 cm EC e to 30–60 and 30–58 dS·m −1 , respectively. Higher water salinity reduced desalination rate, pH and relative bicarbonate content, but increased SAR. Each 1 dS·m −1 increase in water salinity decreased the 0–40 cm desalination rate by 0.55%. Even 34.0 dS·m −1 water achieved efficient leaching, and irrigation salinity should be reduced as soil salinity declines. These findings provide an experimental basis for reclaiming extremely heavy saline soils with ultra–high‐salinity water.