Objective To investigate the effects of intermittent drip irrigation system with two point sources on soil water and salt distribution characteristics, and to provide theoretical basis and practical guidance for soil water and salt regulation of intermittent drip irrigation.
Methods Taking the typical cotton soil in Tarim Irrigation area, Alar Reclamation area, southern Xinjiang as the research object, a simulated two-point soil box infiltration test was carried out with the titer spacing of 30 cm and the titer flow rate of 1.2L/h, and the distribution characteristics of soil moisture peak and water and salt in the wetted body were compared and analyzed under the combined treatment of different intermittent irrigation time and one irrigation duration. Three levels of irrigation interval time were set in the experiment, namely 1, 2 and 3 d. Three levels of irrigation duration were set, namely 3, 4 and 5 h, and there were 6 treatments in total.
Results The wetting front curve of the two-point source infiltration process gradually converges from two semi-ovals to form a saddle shape, and eventually evolves into a semi-ovals with the horizontal infiltration length greater than the vertical infiltration depth. The uniformity coefficient of soil moisture area and moisture content in T3 treatment was the largest. The mean value of soil water content and salt content in the intersection section were higher than those in the droplet section, and the mean value of salt in the intersection section increased by 15.61%~45.29%, and the increase in T3 treatment was the least. Compared with T6 treatment, the mean moisture content in moist body of T1, T2, T3, T4 and T5 treatment was increased by 0.78%, 2.20%, 2.72%, 1.09% and 3.32%, respectively. Compared with T6 treatment, the average desalting rate at the drop head and intersection area of T1, T2, T3, T4 and T5 treatment increased by 12.27%, 25.54%, 38.35%, 25.39%, 37.41% and 8.30%, 18.43%, 30.76%, 10.11% and 30.28%, respectively.
Conclusion Based on comprehensive consideration, it is recommended to adopt the drip irrigation system with the intermittent irrigation time of 3 d and the duration of one irrigation time of 5 h, which can realize the efficient management of soil water and salt.
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