银川平原永宁灌区土壤水盐分布特征研究

Distribution Characteristics of Soil Water-salt in Yellow River Irrigation Area of Yinchuan Plain

为了揭示银川平原灌区降雨(灌溉)入渗条件水盐运移机制,以永宁灌区为例,采用水热盐传感器监测土壤水分、温度、电导率,分析了试验区0~270 cm土壤的水盐时空变化规律。结果表明:(1)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,不同季节的温度日变化呈现不同的特征。浅层20 cm土壤温度受气温影响变化明显,同时受降雨(灌溉)入渗、蒸发的影响,体积含水量和电导率变幅最大。(2)随着深度的增加,降雨对土壤水分的影响逐渐减弱,影响时间存在滞后性,随着入渗深度的不同,盐分积累的深度不同;灌溉后土壤水分除了蒸散发消耗,还存在较明显的下渗,使得土壤盐分随水分淋溶到深层土壤,50~70 cm土壤发生脱盐和积盐的交替过程。该分析结果对合理利用农业水资源、实现农业节水灌溉有重要意义。

In order to reveal the mechanism of water and salt transport under rainfall(irrigation)infiltration conditions in the irrigated area of Yinchuan plain,a TDR sensor is used to monitor the soil moisture,temperature and electrical conductivity,and the temporal and spatial characteristics of water and salt in 0—270 cm soil in the experimental area are analyzed.The results show as follows:(1)The effect of air temperature on soil temperature decreases with the increase of soil depth.The daily temperature changes in different seasons.The temperature in 20 cm soil is significantly affected by the air temperature.The water content and electrical conductivity change the most which is due to the rainfall(irrigation)water infiltration and evaporation.(2)With the increase of soil depth,the impact of rainfall on soil moisture gradually weakens.The depth of salt accumulation is happened according to the depth of infiltration.The obvious infiltration causes the soil salinity to leach into the deeper soil with water movement.The alternating process of desalting and salting is observed at 50—70 cm soil.The analysis results are of great significance for rational utilization of agricultural water resources and realization of agricultural water-saving irrigation.