Spatial variability of soil salinity profiles in cotton field under mulch drip irrigation

[Objective] Soil salinization is one of the important affecting factors to agricultural development in arid area. Soil salinity has strong spatial variability. Xinjiang is located in the northwest of China and belongs to the arid to semi-arid area. The mulched drip irrigation technology is widely adopted to save irrigation water. However, the land salinization in Xinjiang region is severe. Therefore, studying the spatial variation characteristics of soil salinity under drip irrigation under film is of great scientific significance for efficient water conservation and salt control in the arid area of Xinjiang. [Methods] In order to study spatial variability of soil salinity in cotton field under mulch drip irrigation, we conducted field experiments to monitor the soil salinity profiles at small scale in Paotai experiment station and Bazhou experiment station, and applied statistical and geostatistical methods to analyze the characteristics of soil salinity profiles based on the soil-water flow system in cotton field under mulch drip irrigation. [Results]The results indicated that the variation coefficient of soil electrical conductivity in the three profiles was about 0.54~0.76. The variation of topsoil electrical conductivity was largest, and the degree of spatial variability decreased with depth. Soil electrical conductivities had a strong spatial correlation in the three sections. Spatial variability was mainly caused by structural factors, and random factors accounted for 3.53%, 5.03% and 6.61%. Soil electrical conductivity characteristics across the profile exhibit low conductivity in shallow layers, moderately high conductivity in intermediate zones, and high conductivity in deep layers. Horizontally, conductivity is higher near drip lines, between plastic mulch strips, and in wide rows, which correlates with factors such as water flow systems and soil particle composition. The soil salinity of cotton field in Paotai experiment station was higher than that in Bazhou experiment station. The soil electrical conductivity was higher than 7.7 mS/cm, which had a negative effect on the cotton. [Conclusion] The research can provide scientific guidance for high efficiency of water and soil saving measures in arid area and application of precision agriculture.