Characteristics and numerical simulation of irrigation leaching and salt discharge in winter with different groundwater depth
In order to explore the distribution characteristic of winter irrigation leaching salt and the law of salt discharge under different groundwater depths in saline soil,winter irrigation leaching experiments with different groundwater depths were carried out in Korla,southern Xinjiang,from 2022 to 2023.The groundwater depths were set at 2.0 m and 3.0 m,and the winter irrigation was the alternate year winter irrigation and continuous use of winter irrigation.The HYDRUS-2D water salt movement simulation model was established,and the salt discharge characteristics and appropriate leaching quota under different groundwater depths and winter irrigation leaching conditions in saline soil were analyzed.The results showed that the average desalination rate of 0～60cm soil layer under continuous use of winter irrigation with different groundwater depths was significantly higher than that of the alternate year winter irrigation(P<0.05),and the groundwater depth was negatively correlated with the leaching salt discharge of winter irrigation.The cumulative salt discharge of the treatment with groundwater depth of 2.0 m was 1.5～2.0 times higher than that of the treatment with groundwater depth of 3.0 m under different winter irrigation.The determination coefficient of drainage and salt discharge of the HYDRUS-2D water salt movement simulation model was 0.914～0.987,and the measured value of soil is in good agreement with the simulated value;the soil desalination rate per cubic meter of water gradually increased with the increase of irrigation amount under different groundwater levels,and the deeper the groundwater depth,the smaller the impact on the soil salt in the rhizosphere layer before the next spring sowing.It was more suitable for moderately salinized soil with groundwater depth less than 1.5 m and winter irrigation quota of 270 mm.The research results provided references for the formulation of groundwater table burial depth and winter irrigation leaching scheme under different salinization conditions in northwest arid area in China.
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