The impact of different configurations of subsurface drainage pipes on soil water and salt dynamics and the efficacy of salt leaching through drainage during the spring-to-autumn irrigation season in southern Xinjiang
To explore the impact patterns of different subsurface drainage pipe layouts in southern Xinjiang on soil water and salt changes during the"spring irrigation-autumn irrigation"period,and to clarify the appropriate subsurface drainage pipe layout parameters for saline-alkali land management in the local area,this study conducted saline leaching experiments under different subsurface pipe arrangement parameters in May and September 2023.Six treatments were set up,including no subsurface pipes(CK),a spacing of 20 m with a burial depth of 1.0 m(A1),a spacing of 20 m with a burial depth of 1.2 m(A2),a spacing of 30 m with a burial depth of 1.2 m(A3),a spacing of 40 m with a burial depth of 1.2 m(A4),and a spacing of 20 m with a burial depth of 1.5 m(A5).The soil water and salt content,as well as the subsurface pipe drainage flow and electrical conductivity,were measured before and after the leaching.The study analyzed the dynamics of soil water and salt,along with the efficacy of drainage and salt removal within the subsurface drainage system.The results are as follows:the distribution pattern in the soil profile shows water content decreasing from the top to the bottom,while salt content exhibits the opposite trend.Following two leaching events,the phenomenon of soil salt content aggregation was markedly diminished,resulting in a 44.83%reduction in the average salt content of the 0-20 cm soil layer across all treatments.The drainage flow rate rapidly increases to a peak value and then gradually decreases.The discharge conductivity is relatively stable during the discharge process.Compared with the control(CK),the desalination rates in the 0-60 cm soil layer for treatment A5 showed significant increases of 436.88%and 404.27%after two leachings,respectively.The salt removal effect of A1-A5 treatment was evaluated by TOPSIS comprehensive evaluation method,and A5 treatment was the best in both evaluations.Under the conditions of this experiment,the subsurface pipe spacing of 20 meters and a burial depth of 1.5 meters can effectively improve the efficiency of subsurface drainage and promote soil desalination.This method can be widely promoted and used in the loess-like loam region of southern Xinjiang.
subsurface drainage for saline removalsoil water and salt dynamicsdesalination ratedrainage and saline removal per unit areaspring irrigationautumn irrigation
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