Synergistic Regulation of Soil Water–Salt Transport by Irrigation Quality, Quota, and Texture

This study establishes a synergistic Texture–Quota–Salinity (T–Q–S) model to optimize soil water–salt dynamics in arid agricultural systems. Key findings reveal a sand content threshold (S0 = 45.2%) governing salt transport efficiency: (1) Sandy soils (S > 50%) exhibit high leaching capacity, enabling the use of saline water (4 g·L−1) with a 270 mm quota to achieve >75% desalination. (2) Threshold soils (S ≈ 45.2%) balance leaching and retention, maximizing nutrient conservation under brackish water (2 g·L−1) and 260 mm irrigation. (3) Clayey soils (S < 30%) require freshwater (≤2 g·L−1) and reduced quotas (≤230 mm) to mitigate surface salinization. The S0 threshold enables precise irrigation strategies: deep leaching in sandy soils, balanced management in threshold soils, and salt-suppression in clayey soils, enhancing water efficiency by 25% while controlling root zone salinity.