Effects of Plastic Film Mulching on Temporal-spatial Migration of Soil Moisture in Drip Irrigation Cotton Fiel

【Objective】 To compare and analyze the law of soil moisture movement in time and space dimension in the film-mulching and non-film drip irrigation cotton fields. 【Method】 Film-mulching drip irrigation and non-film drip irrigation were used as experimental treatments. The 5TE soil moisture temperature sensors were used to collect soil moisture data during the whole growth period of cotton in real time, and software such as Voxler and Surfer were used to perform temporal-spatial interpolation, 3D visualization and slicing of the soil moisture grid data. 【Result】 The overall soil moisture content of drip irrigation under film-mulching was higher than that of drip irrigation without mulch; In the vertical direction, the migration between the different depths of the drip irrigation under the mulch accelerated, and the soil moisture content increased with the increase of depth. The water content in the bottom soil (80-100 cm) was the largest, while the drip irrigation without mulching the soil moisture exchange was not active, and the moisture was mainly concentrated in the surface soil (0-20 cm); In the horizontal direction, there was no significant difference in the soil moisture content of the near root system and the far root system soil layer between the two treatments; In the time dimension, as the growth process of cotton advanced, the soil moisture content of drip irrigation under the mulch showed an overall upward trend. The rate of soil moisture loss before drip irrigation (June 20) was 3×10^-4 m³/(m³·d), and maintained 30×10^-4m³/(m³·d) from June 20 to August 11 (after drip irrigation), then increased to 30×10^-4m³/(m³·d) from August 11 to August 26 (the last drip irrigation). After that, it was reduced to 30×10^-4m³/(m³·d). For the soil moisture of the non-film drip irrigation treatment, it was relatively stable, and the water loss rate before drip irrigation was 0.7×10^-4m³/(m³·d), and 10×10^-4m³/(m³·d) after drip irrigation. 【Conclusion】 The film-mulching treatment can make the soil moisture move down from the surface layer, and the bottom layer (80-100 cm) has the highest volume of water; while in the horizontal direction, there is no significant difference in soil moisture between the near-root side and the far-root side of the two treatments; in the time dimension, the film-mulching treatment increases the fluctuation of soil moisture in drip irrigation cotton fields, which increases the water extinction rate, while the non-film drip irrigation treatment keeps the water extinction rate stable. The results of this study provide the theoretical basis and technical support for the cotton precision irrigation and the filmless cotton cultivation technology.