Abstract
With the popularization and development of drip irrigation under film, the problem of secondary soil salinization in Xinjiang is becoming more and more serious. To explore water and salt transport in drip irrigation under mulch and drainpipe drainage, drainage tests of drainage ditches in saline-alkali soil in the Xinjiang 112 group were used to monitor soil salinity changes by controlling field irrigation. Then, a HYDRUS (PC-Progress, Prague, Czech Republic) numerical model was used to simulate and analyze the changes in salinity during cotton growth and the autumn salt return stage in saline-alkali soil under drainage conditions. The agreement between the simulated and measured values was high, and the model parameters were reliable. During the growth period of cotton, the salinity continued to decrease, and the salt began to return after the harvest. Compared with before planting, in the 0–80 cm soil layer, the average desalinization rate reached 43.52% under the mulching films, and the average desalinization rate reached 13.83% under and between the mulching films. After the cotton was harvested, salt returned to the upper layer of soil. However, it still showed a decrease compared with the level before sowing. The average salt content of 0–80 cm soil decreased by 5.14%, and the average salt content of 0–200 cm decreased by 2.60%. This shows that the total salt content in soil will continue to decrease after long-term use of drip irrigation and underground pipe drainage.
Highlights
Drip irrigation technology under mulch has become popular in Xinjiang; the original drainage canals were gradually abandoned, and the "drip irrigation without drainage" pattern was formed [1,2]
It could be seen that the soil salt content in the root layer of Figure 8 is a graph showing the change in salinity in the 0–80 cm soil layer over time, taking the cotton decreased during the whole growth period, and the degree of decrease decreased as soil depth film-covered area as the sampling point
The average soil salt content (EC 1:5) in the surface layer decreased by 67.32%, in the 20 cm cotton decreased during the whole growth period, and the degree of decrease decreased as soil soil layer by 48.58%, in the 40 cm soil layer by 46.22%, in the 60 cm soil layer by 22.68%, and in the 80 depth increased
Summary
Drip irrigation technology under mulch has become popular in Xinjiang; the original drainage canals were gradually abandoned, and the "drip irrigation without drainage" pattern was formed [1,2]. This model can moisten the root layer in a short time and temporarily desalinate the root layer. Reported that after the end of the cotton growth period, soil salinity increased in the top 60 cm and accumulated strongly at a depth of 0–20 cm between the mulching films. Yi et al [7] reported that salts gradually accumulated with the prolongation of drip irrigation under mulch, and the accumulated salts gradually migrated to the surface before irrigation
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