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| Dynamic distribution of water, salt and temperature in soil profile during freezing and thawing in cotton field under mulch drip irrigation |
| LIAO Hai1,2, LI Xianwen1,2, CHEN Junying1,2* |
| 1. College of Water Resources and Architectural Engineering, Yangling, Shaanxi 712100, China; 2. Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas, Ministry of Education, Northwest A&F University, Yangling, Shaanxi 712100, China |
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Abstract In order to reveal the dynamic changes of soil water, salt and temperature in cotton field under mulch drip irrigation during freeze-thaw period in arid area. The Hydra water, salt and hydrothermal system was used to monitor the liquid moisture, temperature and conductivity at the depth of 15 cm, 25 cm and 40 cm between wide rows, narrow rows and inter-membrane during freeze-thaw period. The dynamic change process of soil water, salt and heat during freeze-thaw period was analyzed. The results show that the dynamic changes of liquid moisture, conductivity and temperature in the same position at different depths were consistent. During the freeze-thaw period, the law of salt vertical migration is that the salt in deep soil moves to the surface layer. The freeze-thaw effect redistributes the salt and aggravates the salt content in the soil at the depth of 40 cm, and increase range of conductivity is 20-80 μS/cm. The relationship between the conductivity values in different positions before and after freeze-thaw is: wide row>narrow row>between films. In the process of freezing and thawing, there is a strong positive correlation between soil temperature, liquid moisture and electrical conductivity at different positions(P<0.01), and the correlation coefficient is above 0.74. However, there is also a strong multivariate linear function relationship between electrical conductivity and temperature and liquid moisture(P<0.01), and the number of phase relationships is greater than 0.90. Freezing and thawing are not coincident processes, but the bifurcation points will appear in the process, which will appear near -1 ℃. The research results have important refe-rence significance for formulating reasonable water and salt management system in non-growth period.
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Received: 27 July 2020
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