格库铁路生态防护林区咸水滴灌风沙土盐分运移特征研究

Study on the Characteristics of Salt Migration in Sandy Soil Under Saline Groundwater Drip Irrigation in Shelter Forest Area along the Golmud-Korla Railway

土壤的盐分含量是影响植物生长的重要因素,盐分分布和累积状况关系植物的持续生长。梭梭(Haloxylon ammodendron)是荒漠地区极为抗旱耐盐的荒漠植物种,可以忍耐较高矿化度的咸水灌溉,为干旱区生态建设的重要植物种。开展了室外种植器种植梭梭苗的模拟实验,分别用淡水(CK)和矿化度20、30、40、50 g/L咸水进行灌溉。结果表明:(1)高矿化度水滴灌造成风沙土盐分含量和离子组成的显著变化,由非盐渍土逐渐转变为轻度盐渍土;表层盐结皮盐分含量远高于下层,且土层越深,土壤盐分含量越高,兼有表层集聚性与深层累积性特点;灌溉水矿化度越大,土壤积盐程度越大;土层越深,土壤pH值越低。(2)土壤中盐分以Cl^(-)、Na^(+)为主,也含有较多SO_(4)^(2-)离子;从表层至底部,Cl^(-)、Na^(+)、Ca^(2+)、K^(+)、Mg^(2+)和SO_(4)^(2-)6种离子含量先突降,而后随着土层加深,离子含量不同程度增加;CO32-和HCO3-具有明显的表层集聚特性。(3)当灌溉水矿化度在20~30 g/L时,梭梭仍然能较好生长,但矿化度30~50 g/L时,梭梭仍能够存活,但生长受到了明显抑制。研究结果对干旱荒漠地区地下咸水资源的开发利用和生态建设实践具有一定的参考价值。

Haloxylon ammodendron is an important desert plant in maintaining ecological balance in desert regions.In the area where salt water is abundant but fresh water is insufficient,it is of great significance to study the distribution and accumulation of salt in soil profile by using salt water to irrigate ammodendron.This study adopted the method of combining outdoor soil column simulation experiment with indoor analysis,and adopted the water irrigation treatment with five salinity levels of fresh water(CK),20 g/L、30 g/L、40 g/L、50 g/L.The experimental results showed that:①High salinity water drip irrigation has a significant impact on soil salt content and ion composition.In general,the degree of soil salt accumulation increases with the increase of salinity of irrigation water.In the vertical direction,the salt content of the surface salt crust soil is much higher than that of the subsoil,and the salt content of the subsoil on the whole increases with the deepening of the soil layer,while the soil pH value,on the contrary,tends to decrease with the deepening of the soil layer,and the soil gradually changes from non-saline soil to mildly saline soil.②Soil salinity is mainly composed of Cl^(-)and Na^(+),and contains more SO_(4)^(2-)ions.The content of Cl^(-),Na^(+),Ca ^(2+),K^(+),Mg ^(2+)and SO_(4)^(2-)six ions from topsoil to bottom experienced a sudden drop.Then,as the soil layer deepened,the content of ions increased to different degrees,presenting surface accumulation and deep accumulation characteristics.CO 32-and HCO 3-presented surface accumulation characteristics.③When the salinity of irrigation water is between 20~30 g/L,ammodendron can still grow well,but more than 30 g/L,although ammodendron can survive,its growth is obviously inhibited.This study has theoretical significance and application value for rational exploitation and utilization of high salinity groundwater in arid areas and construction of shelterbelt in desert areas.