Effects of Winter Irrigation on Soil Water-heat-salt Migration and Crop Growth During Freezing-Thawing Period in Qingtongxia Irrigation District of Ningxia

Abstract

[Objective] The effects of winter irrigation on soil water-heat-salt migration and crop growth during the freezing-thawing period were analyzed in order to provide a scientific basis for controlling soil salinization, and to ensure food security. [Methods] Statistical analysis and visualization methods were used to compare and analyze soil water-heat-salt migration and crop growth in winter irrigation and non-winter irrigation areas based on meteorological, soil physicochemical indicators, and crop growth data in an experimental field in the Qingtongxia Irrigation District of Ningxia from 25 October 2018 to 3 October 2020. [Results] Soil temperature changes in the Qingtongxia Irrigation District lagged behind air temperature changes, and the shallow surface soil temperature was more significantly affected by air temperature changes. The soil gradually froze from the surface downward and the freezing depth deepened as the temperature decreased. The frozen layer of soil thawed simultaneously from the soil surface and the bottom of the measurement profile during the thawing period. The entire soil freezing and thawing period lasted for 98 days. The soil moisture content increased significantly after irrigation. During the freezing period, irrigation decreased the temperature of each soil layer by 0.1—1.1 ℃. The variation trends of soil temperature and moisture in different soil layers during the winter irrigation period were basically the same as those during the non-winter irrigation period. After winter irrigation, the salinity of each soil layer decreased, especially in the 0—30 cm soil layer, and salinity decreased significantly. However, after the freezing-thawing period, salt accumulated in the soil. Winter wheat grew taller and corn grew faster in the winter irrigation farmland than in the non-winter irrigation farmland. Average wheat and corn yields increased by 20.64% and 4.20%, respectively, in the winter irrigation farmland. [Conclusion] Winter irrigation affected the distribution of soil water, heat, and salt, and effectively reduced soil salinity, resulting in increased crop growth and yield (especially wheat yield) in the Qingtongxia Irrigation District.

Keywords

• qingtongxia irrigation district
• winter irrigation
• freezing-thawing
• soil water-heat-salt
• crop growth