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| DOI：10.13522/j.cnki.ggps.2025063 |
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| Salt accumulation and its controlling factors in saline soil profile of Yellow River Delta |
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HAN Xing, PAN Yinghua, CHEN Xiaobing, DONG Xiaoyan, SUN Kaixiao
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1. School of Resources and Environmental Engineering, LuDong University, Yantai 264025, China;
2. Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China
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| Abstract: |
| 【Objective】Soil salinization is a major threat to agricultural productivity in the Yellow River Delta, where shallow groundwater and high soil salinity often result in salt accumulation in the root zone. This paper experimentally investigates the mechanisms underlying salt accumulation in this region.【Method】The experiment was conducted using soil columns packed with clay loam with a salt content of 37.24 g/kg taken from the Yellow River Delta. It compared nine treatments, in which the salt content of the groundwater was 0 (K1), 5 (K2) and 10 g/L (K3), and the groundwater table was controlled at the depths of 10 (S1), 30 (S2) and 50 cm (S3). For each treatment, we measured the capillary rise of groundwater, groundwater uptake rate, cumulative groundwater uptake, and water-salt distribution in the soil profiles.【Result】① When the groundwater table depth was the same, groundwater salt content had no significant effect on the height of capillary water rise, groundwater uptake rate, cumulative groundwater uptake, and volumetric soil water content. Increasing groundwater table depth delayed the advancement of the wetting front, increased the cumulative groundwater uptake, and decreased the topsoil water content. ② When the groundwater table depth was the same, there was a significant difference in salt content in the lower part of the soil profile between different groundwater salt contents (p＜0.05), but not in the upper part of the soil profiles. Regardless of groundwater table depth, salt accumulated in the soil surface in all treatments. Over 60% of the soil profiles comprised desalinated zones, with the salinized zone increasing as the groundwater tables increased. ③ After the groundwater reached the soil surface via capillary rise, the inflection points in the distribution of soil water and salt along the soil profile were the same when the groundwater table depth was the same, located at the depth of 4-6 cm, 16-18 cm and 26-28 cm for S1, S2 and S2, respectively. Above these critical locations, soil volumetric water content and soil salinity were linearly correlated (p＜0.05).【Conclusion】When soil evaporation was weak, salt accumulation in the soil surface was primarily driven by capillary rise of groundwater and modulated by the dynamic equilibrium between salt dissolution, diffusion and adsorption in the soil profiles. |
| Key words: saline soil; capillary water; wetting front; surface salt accumulation |
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