Effects of salts on water evaporation and soil fracture development
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DOI:10.7606/j.issn.1000-7601.2024.04.10
Key Words: soil salt  soil evaporation  soil desiccation cracking  cumulative evaporation
Author NameAffiliation
FENG Haoxuan Key Laboratory for Agricultural Soil and Water Engineering in Arid Area of Ministry of Education, Northwest A&F University, Yangling, Shaanxi 712100, China 
WU Liance Key Laboratory for Agricultural Soil and Water Engineering in Arid Area of Ministry of Education, Northwest A&F University, Yangling, Shaanxi 712100, China 
XING Xuguang Key Laboratory for Agricultural Soil and Water Engineering in Arid Area of Ministry of Education, Northwest A&F University, Yangling, Shaanxi 712100, China 
MA Xiaoyi Key Laboratory for Agricultural Soil and Water Engineering in Arid Area of Ministry of Education, Northwest A&F University, Yangling, Shaanxi 712100, China 
LI Xianwen Key Laboratory for Agricultural Soil and Water Engineering in Arid Area of Ministry of Education, Northwest A&F University, Yangling, Shaanxi 712100, China 
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Abstract:
      Revealing the drying and cracking mechanism of saline alkali soil can provide a theoretical basis for the formulation of precise irrigation systems based on crack networks in arid and semi\|arid saline alkali areas. This study set up 5 types of soil salt content (0, 0.3%, 0.6%, 1%, 2%, respectively recorded as CK, T3, T6, T10, T20) treatments to conduct constant temperature soil evaporation experiments, explore the impact of salt content on soil evaporation process, and quantitatively analyze the geometric characteristics of soil shrinkage crack network during evaporation process using digital image processing technology. The results showed that: (1) The evaporation processes of different treatments had similarities, that is, the evaporation process included a linear stage and a nonlinear stage, but the proportion of each evaporation stage to the total evaporation stage was different. T20 entered the deceleration rate stage at the earliest, indicating that salt causes a decrease in soil permeability. (2) The cumulative evaporation decreased with the increase of soil salt content, namely CK>T3>T6>T10>T20, indicating that salt can inhibit soil evaporation. (3) As the soil salt content increased, the water content of the cracking decreased, and the crack area and crack length gradually decreased and then stabilization. The interaction between water evaporation and surface cracking was manifested by the chemical effects of free Na+ on soil particles during water loss and the physical effects of precipitated Na2SO4 crystals on soil pores. (4) Correlation analysis showed that cumulative evaporation and soil moisture was significantly positively and negatively correlated with surface crack, respectively. The correlations between cumulative evaporation and crack parameters were overall higher than that between soil water content and crack parameters.