Influence of Drip Irrigation and Soil Compaction on Soil Water and Salt Transport in Saline-Alkali Farmland of the Yellow River Delta

The Yellow River Delta region suffers from pronounced soil salinization, attributed to its shallow groundwater depth and an evaporation rate that exceeds precipitation. Flood irrigation, widely adopted locally as the primary means of salt leaching, further aggravates pressure on the already limited freshwater resources. This study investigates the effects of combined drip irrigation and soil compaction on soil water and salt movement in saline-alkali farmland of the region, aiming to propose a new approach for regional water conservation and salt control. Field experiments and model simulations were integrated in this research. Based on experimental data collected from cotton fields over two consecutive years, the Hydrus-2D model parameters were calibrated and validated. Several scenarios were then simulated, including conventional irrigation, conventional irrigation with soil compaction, and drip irrigation with soil compaction, to analyze soil water and salt dynamics under different conditions. The results show that drip irrigation delivers water precisely to the plant root zone through small, frequent applications, reducing evaporation and deep percolation losses. Soil compaction effectively increases post-irrigation soil volumetric water content and, within a reasonable “compaction threshold,” significantly inhibits upward salt movement. The combined use of drip irrigation and soil compaction reduces both the water required for pre-sowing salt leaching in the root zone and the irrigation demand during the crop growth period, thereby markedly improving water use efficiency. This study provides a novel strategy for regulating soil water and salt in saline-alkali farmland, which can help alleviate agricultural water scarcity in the Yellow River Delta region.