石羊河中游荒漠绿洲区土壤水分的分布特征

通过田间实验,研究了不同土壤层颗粒组成、土壤水分的分布特征及不同土壤层间土壤水分的关联性。结果表明：（1）土壤颗粒组成决定了不同土壤层的持水性能,是导致土壤水的分布及运动方式发生变化,影响水分在土壤中滞留时间的根本原因,土壤层中的砂砾所占百分数越大,粘粒含量就越少,含水率就越小,壤土中的土壤水分滞留时间远大于砂质土壤。（2）试验区3m内土壤层可分为水分散失带、水分滞留带和水分过渡带,水分滞留带是土壤水分暂时贮存的重要土层,也是为植被提供深层土壤水分的直接来源,对植被的生长及农作物生产有重要的影响,而土壤中粉砂质粘粒含量的高低决定了水分过渡带的形成及其对水分调节能力的强弱。（3）在地下水深埋区,灌溉是土壤水分重要的补给来源,也是影响土壤水分重分布的主要因素,在天然降水量大部分为无效降水的情况下,灌溉水是土壤水唯一的补给源。补给水分滞留带的灌溉水量的多寡,直接影响着水分滞留带的调节能力及作物和植被的生长。

Distribution Characteristics of Soil Water in Hungriness Region in Middle Reaches of Shiyang River

The particle composition of the different soil layer,distribution characteristics of the soil moisture and the relevancy of the soil water in different soil layers were investigated in the field experiment.Results showed:(1) It was crucial reason that the particle composition of the soil layer decided the capability of the soil moisture retention,which reflected on the variety of the distribution and the movement actions of the soil water and affected the detention time in the soil.The percentage of the grit was higher in the soil layer,and the percentage of the clay content was lower,and the soil moisture was smaller.The detention time of the soil water in the loam was longer than in the sand soil.(2)The region of the soil moisture loss,the region of the soil moisture detention,and the region of the soil moisture transition were named for the soil layer from surface to 3 m depth in the field experiment district.The region of the soil moisture detention was the place of the soil water reserving,and provided the water resources for the plant.The influence of the particle content of the silty loam was great crucial for forming the region of the soil moisture detention and the capability of the soil moisture regulated.(3) With the deep under ground water table,irrigation water supplied the soil water and affected the redistribution characteristics of the soil moisture,which influenced the regulating capability of the region of the soil moisture detention and the growth of the crop and plant.