塔里木河下游典型绿洲滴灌防护林地土壤水盐时空动态

Spatio-temporal Variations of Soil Water and Salinity in Drip Irrigation Shelterbelt in a Typical Oasis in the Lower Reaches of the Tarim River

通过野外定位观测,对塔里木河下游典型绿洲防护林地灌溉周期内、不同滴灌年限以及不同质地类型土壤水盐动态进行监测分析。研究结果表明:①绿洲幼龄防护林地土壤水盐变化属于灌溉周期型;灌后土壤湿润体呈"半椭球型"分布,积盐区位于湿润峰附近;当前防护林(沙壤土)滴灌周期为10d较为合适。②实施滴灌1a、2a和5a林地(沙壤土)土壤水分亏缺量逐年增大;0～20cm土层随滴灌年限的增大先脱盐后积盐,20～120cm土层均表现为脱盐。③滴灌5a后,粉黏土林地表层板结层的形成显著抑制40～60cm土壤水分蒸发,盐分呈"表聚型"分布;细沙土林地土壤持水性差,各土层盐分呈"均匀型"分布;沙壤土林地持水性较细沙土林地略高,盐分呈"波动型"分布。

Fixed-position observation of soil water and salinity in shelterbelts with different soil texture was conducted in a typical oasis in the lower reaches of the Tarim River.（1） Variation of soil water and salinity in young shelterbelt fell into an irrigation period type.The soil wetting front was a semi-ellipsoid in shape after drip irrigation,and the salt accumulation zone was on the edge of soil wetting front.A ten-day irrigation period was appropriate for sandy loam in the shelterbelt.（2） Soil moisture deficit increased gradually with drip irrigation time for sandy loam shelterbelt.The salinity in 0-20 cm depth of soil reduced first then increased,that in 20-120 cm reduced consistently with the increase of irrigation time.（3） Five years after drip irrigation operation,the compacted surface soil significantly restrained the moisture evaporation from 40-60 cm depth of silt clay soil,and the soil salt was concentrated in the upper layer.Fine sandy soil had poor water holding capacity,which contributed to the even distribution of salt in soil.The water holding capacity of sandy loam soil was slightly higher than that of fine sand soil,and its salinity distribution fluctuated in different soil depth.