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.
Dong et al. (Thu,) studied this question.