Abstract: This paper researched the effect of temperature on soil water and salt migration in cotton field during freezing thawing periods under drip irrigation in north Xinjiang, China. The results showed that the effect of air temperature on soil temperature was continuously decreased with the increase of soil depth, the lag time was ceaselessly lengthened, and the soil thawing rate was much higher than soil freezing speed. The soil thawing rate in topsoil was higher than that in subsoil. Soil moisture content was strongly affected by temperature. During freezing period, soil water migrated slowly from nonfrozen layer to frozen layer, and it migrated from subsoil to topsoil under the effect of evaporation during thawing period. Analyzed result showed that temperature affected indirectly the soil salt migration. During freezing period, soil water migrated slowly, and the change of soil salt migration was low; during thawing period, soil water migrated actively, and the change of soil salt migration was high. Under rapid temperature increase, soil water migrated continuously. Sustainable cotton cropping was seriously affected due to the upward migration of soil water in soil layer of 120-150 cm under drip irrigation.

Key words: cotton field, drip irrigation, soil freezing and thawing, soil temperature, soil water and salt migration, Shihezi, Xinjiang