土壤冻融温度影响下棉田水盐运移规律

以新疆北部常年膜下滴灌棉田为研究对象，探讨整个冻融过程中温度对土壤水盐运移规律的影响。研究结果表明：气温对土壤温度的影响随着土壤深度的增加而不断减小，滞后时间不断延长，并且气温对冻土的消融速度远远快于冻结速度，上层冻土消融速度快于下层。土壤水分受温度的影响较大，在冻结期，土壤水分从非冻结层向冻结层缓慢运移；在消融期，下层土壤水分在蒸发作用下不断向上运移。通过监测分析得知，温度间接影响盐分运移，在冻结期，土壤水分运移缓慢，土壤盐分运移变化较小；在消融期，土壤水分运移较为活跃，土壤盐分运移变化较大。在温度快速上升的情况下，土壤水分不断上移， 120～150 cm土壤盐分迅速向上扩散，上层土壤盐分不断增加，威胁膜下滴灌棉田可持续种植。

Soil Water and Salt Migration in Cotton Field under Soil Freezing-Thawing Temperature

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.