干旱区绿洲土壤盐渍化分析评价

Analysis and evaluation of soil salinization in oasis of arid region

内蒙古阿拉善左旗贺兰山西侧是我国典型的干旱区,土壤盐渍化现象严重。因此,本次研究对该区存在的土壤盐渍化生态环境地质问题进行评价,分析了土壤盐渍化影响因素,提出了盐渍化防治措施。结果表明:(1)研究区内盐渍化土壤占全区面积的32%,且pH值高,碱化度大,具有盐化与碱化同时进行的双重特性;(2)土壤可溶性离子组成以Na^+和SO_4^(2-)、Cl^-离子为主,Na_2SO_4和NaCl是造成该土壤碱化和性质恶化的主要因素;(3)土壤盐分季节变化明显;(4)土壤盐渍化的形成原因主要是残余积盐和灌溉的影响;(5)在改良利用方面,应在综合规划与合理布局的基础上,因地制宜的发展农林牧业,尽快停止使用不符合标准的水进行灌溉,防止生态环境遭受破坏与盐渍化加剧,已垦的盐渍土耕地,尤应重视土壤培肥。

Alashan Prefecture pastoral area of Inner Mongolia was atypical arid area, where mineral, land and agricultural resources were very rich. However, a large area of soil was salinized due to irrational development, which resulted in grassland degradation and desertification increasing, and seriously obstructed and constrained sustainable development of local agricultural economy. Soil salinization has become one of the important factors to limit economic sustainable growth. Therefore, it is important to analyze and evaluate soil salinization of this typical arid oasis. In order to find out the distributing characters of soil salinization, the 61 soil profiles were emplaced proportionally in studying area. Soil salinity, pH value and ion contents of 0 -10 cm, 10 -20 cm,20 -40 cm,40 -70 cm,70- 100 cm and 100 -150 cm soil layer were analyzed. At the same time total dissolved solid （TDS） of 16 water samples in unconfined aquifer were collected and tested. According to analysis results, the following subjects were studied：soil salinity distribution patterns of plough layer, variety patterns of soil salinity in different seasons, calcium carbonate profile in different layers and mineralization isopleths of unconfined aquifer. Then the influencing factors of soil salinization were analyzed. Prevention measures were provided. The results showed as flows ： （ 1 ） The area of soil salt content which was higher than 1% accounted for 32% of the whole region, and the salt contents of soil in southwest part were higher than that in northeast part, which was consistent with the distribution of the total dissolved solid （TDS） of water in unconfined aquifer. These indicated the phenomenon of soil salinization was widespread and the main reason of soil salinization is due toirrigation water quality. （2） The primary soluble ions were Na^＋ and SO2^4- ,Cl^- , it is reputed that the first cause of soil alkalization is created by NaaSO4 and NaCl. Testing results of pH value show that the pH value of soil in the majority was higher than 8.5, which illuminated it had the double characteristics of salinization and basifieation. （3） The soil salinity represents the significantly seasonal varying. On the soil profile strong lime reaction was obvious from top to down, most of calcium carbonate was accu- mulated in the middle or lower layer, and the accumulated depth of calcium carbonate became deeper and deeper gradually from east to west. （4） In order to amend and develop the saline soil, comprehensive planning and reasonable layout should be needed. Agriculture, forest, and pastures should be developed based on the local conditions. In order to prevent the damage of eco-environment and salinization, in the saline plowland, the soil fertility should be improved. The study results provided a theoretical basis and practical reference for the study region as well as the vast arid area oasis to manage scientifically, use rationally and improve precisely salinized soil.