Abstract: Irrigation with brackish water is of great significance in plain irrigation districts in the Tarim Basin where it is in shortage of water resources. The most serious problem in brackish water irrigation is salt accumulation in soil. The focus is that whether it is necessary to leach salt in soil with winter irrigation or spring irrigation before sowing next year after brackish water irrigation is applied for one year. In this paper, the data of easily dissolvable salts in soil 0-60 cm in depth, monitored in 3 monitoring areas (S1, S2 and S3) before and after spring irrigation in Tarim Township, Yuli County, Xinjiang in 2010 were analyzed, and the indexes of salt tolerance of cotton plant at germination, seedling-budding, flowering-boll and boll-opening stages (7.1, 6.9, 8.2 and 9.2 g/kg respectively) were compared. The results show that soil in cotton field could be desalted to the soil salt content level of satisfying cotton seed germination and cotton plant growth by spring irrigation leaching once every other year in monitoring area S1 and S2 but every year in monitoring area S3. The soil desalting ratios of spring irrigation leaching in the 3 monitoring areas varied in ranges of 11.9%-84.2%, 20.7%-71.1% and 32.9%-78.8% respectively. These results reveal that the desalinization of spring irrigation leaching in these 3 monitoring areas was obvious.

Key words: brackish water, under-film drip irrigation, desalinization of spring irrigation leaching, cotton field, soil salt accumulation, Tarim Basin