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| DOI：10.13522/j.cnki.ggps.2024358 |
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| Effects of freeze-thaw cycles and winter irrigation on soil water and salt transport in irrigation districts in Northern Yinchuan |
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YANG Wu, WANG Bingliang, CHEN Shujuan, LI Wangcheng, LIN Xing
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1. School of Civil and Hydraulic Engineering, Ningxia University, Yinchuan 750000, China; 2. Engineering Research Center for Efficient Utilization of Modern Agricultural Water Resources in Arid Areas, Ministry of Education, Yinchuan 750000, China;
3. Ningxia Key Laboratory of Digital Water Control of Yellow River Water Networking, Yinchuan 750000, China;
4. Service Center of Shizuishan Agricultural Technology Extension Center, Shizuishan 753000, China
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| Abstract: |
| 【Objective】In saline-alkali regions of Northern Yinchuan, freeze-thaw cycles and winter irrigation play a key role in soil water and salt dynamics. This paper experimentally studies how different winter irrigation amounts affect soil water and salt redistribution during freeze-thaw periods, aiming to improve water use efficiency and soil salt management.【Method】Freeze-thaw experiments were conducted in both laboratory and field using moderately saline-alkali soil, with soil in the former taken from Huinong District, Shizuishan City, Ningxia Province. The experiments investigated water and salt migration in soils under ① different freezing temperatures ranging from -13?℃ to -23?℃, ② different initial soil moisture contents ranging from 16% to 23%, and ③ different winter irrigation amounts ranging from 900 to 3 120?m3/hm2 in the laboratory, and from 3 120 ?to 3 900?m3/hm2 in the field. 【Result】① In the early freezing period, soil water was greatly affected by the surface temperature, and the migration rate of the freezing front was fast while liquid water migration was slow. In the late freezing period, soil water was not significantly affected by the surface temperature, and the migration rate of the freezing front was slow while liquid water migration was fast. ② Water migration significantly affected soil salinity, but the two did not occur simultaneously. There was a delay in salinity change following soil water change; soil salt content peaked in the vicinity of the freezing front. ③ In the laboratory experiments, the maximum salt concentration occurred at the depth of 35?, 55 and 95?cm, when irrigation amount was 900, 1 600 and 3 120??m3/hm2, respectively. In the field experiment, there was no salt accumulation under different irrigation amounts, and soil fertility in the following year was similar under different irrigation treatments.【Conclusion】Winter irrigation alters soil water and salt migration significantly, compared to treatment without irrigation. Winter irrigation results in salt leaching; our results suggest that optimizing winter irrigation amount is important to achieve water saving without compromising soil fertility. |
| Key words: Yinbei irrigation district; farmland winter irrigation; seasonal freeze-thaw; water and salt migration |
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