Irrigation using a large amount of water is commonly employed to leach soil salts out of the crop root zone in arid and salinized regions during non-growth periods, such as during spring pre-sowing irrigation (SIR). While soil salts in the root zone decrease after SIR, optimizing the irrigation program across non-growth and growth periods remains a great challenge. This study utilized the HYDRUS (2D/3D) model, validated with field data from Ordos, China (2022–2024), to evaluate soil salinity and sunflower productivity under six strategies combining SIR and drip irrigation (DIR). The irrigation strategies included high and low SIR (225 mm, S H ; 135 mm, S L ), and high, medium, and low DIR (180 mm, D H ; 135 mm, D M ; 90 mm, D L ) during the growth season. The model simulated soil salinity effectively ( R 2 = 0.86, RMSE = 0.30 dS m −1 , M RE = 5.01%). Higher SIR significantly reduced pre-sowing salinity, with the S H treatment lowering EC e by 28.5% compared to S L . When maintaining the same total irrigation depth, combining low SIR with high DIR mitigated salt stress more effectively than high SIR with low DIR, improving crop yield by 18.6% and water productivity by 17.3%. Scenario analysis indicated that while SIR had the most significant impact on reducing salt when accounting for 45% of total irrigation, depths below 150 mm still posed risks to sunflower growth. Therefore, the recommended optimal strategy is a SIR depth of 150 mm combined with a DIR depth of 183 mm, which ensures effective salt control and high productivity while maintaining a low total irrigation depth. • Spring pre-sowing irrigation (SIR) with non-growth period and drip irrigation (DIR) with growth period were evaluated. • The salt dynamics during both growth and non-growth periods were analyzed using the HYDRUS(2D/3D) model. • Soil water-salt balance and water productivity were analyzed under different irrigation strategies. • Simulation showed the optimal strategy was the combination of 45% SIR and 55% DIR. • The irrigation strategy is to recommend a somewhat lower SIR than DIR when irrigation water is limited.
Zhen et al. (Tue,) studied this question.