A global meta-analysis of the effects of irrigation with water containing salts on saline-alkali soils

Irrigation with water containing salts offers promise for alleviating freshwater shortages in saline-alkali regions but presents a trade-off: excessive salt accumulation may induce crop stress, risking agricultural sustainability. Achieving a sustainable balance requires a comprehensive understanding of the interactions among evapotranspiration, soil salinity, soil type, precipitation, groundwater dynamics, crop selection, and irrigation management. In this study, we synthesized data from 81 published articles (1023 paired observations) to assess the effects of irrigation with water containing salts on soil electrical conductivity (EC), soil moisture content (SMC), and crop yield in saline-alkali soils under various environmental conditions and agronomic management practices. Results showed that, compared to freshwater irrigation, irrigation with water containing salts significantly increased soil EC by 26.86 % and SMC by 8.85 %, while reducing crop yield by 21.99 %. Further analysis of categorical variables revealed that freezing saline water irrigation (FSWI) contributed to moisture retention and salt suppression, thereby mitigating yield loss (soil EC: −23.49 %, SMC: 8.64 %, crop yield: −11.59 %). Minimal yield reductions were also observed under specific conditions, including mean annual temperature (MAT) below 10°C, groundwater depth > 1.5 m, irrigation water quantity ranged from 50 % to 75 % of ET₀, and salt-tolerant crop type (e.g., cotton). The Boosted Regression Tree (BRT) model analysis further identified irrigation water salinity, MAT, irrigation water quantity, soil texture and crop type as the key factors regulating crop responses to irrigation with salty water. These findings provide valuable insights into optimizing irrigation strategies for water containing salts, supporting a scientific basis for sustainable agricultural management in saline-alkali regions. • Irrigation with water containing salts increased SMC (8.85 %), soil EC (26.86 %), and reduced crop yield (-21.99 %). • FWSI showed greatest improvements on saline-alkali land (soil EC: −23.49 %, SMC: 8.64 %, crop yield: −11.59 %). • Irrigation water salinity, MAT and irrigation water quantity regulate crop responses to irrigation with salty water. • Scientific irrigation management should account for salinity conditions to prevent salt buildup and soil degradation.