塔河下游典型绿洲灌区不同土地利用类型土壤的盐渍化特征

目的]探明干旱区绿洲不同土地利用方式下土壤的盐渍化特征，为区域土地资源可持续有效利用提供支撑。方法]运用GPS定位技术对塔河下游灌溉用水、地下水以及4种典型土地利用方式下的土壤分不同季节进行调查与采样，并结合室内测定结果，对灌区内的盐分、盐分离子变化特征及其成因进行分析。结果]研究区土壤呈碱性，盐分类型主要为硫酸盐—氯化物型，盐分含量在2.44～118.05g/kg之间，pH值范围在8.05～8.34之间，不同土地利用类型下土壤盐分含量和pH值在各季节的整体变化均表现为：盐荒地>盐碱草地>耕地和林地。从不同土层深度来看，耕地的盐分在6月和10月呈表聚型，在3月和12月无明显规律，盐荒地和盐碱草地在不同季节下不同土层深度的盐分变化均呈明显的表聚型，林地在各季节下无明显规律。研究区受水库地理位置影响地下水水位较浅(1.4～3.51 m),地下水矿化度较高(1.56～21.30 g/L),灌溉用水、地下水中的盐分离子均以Na⁺和Cl^-为主。结论]研究区不同土地利用类型下的土壤盐渍化特征主要是受地表覆盖度、作物种植类型、灌溉事件等...

Soil Salinization Characteristics of Different Land Use Types in a Typical Oasis Irrigation Area of Lower Tarim River

Objective] The soil salinization characteristics under different land use types in extremely arid regions were analyzed in order to provide support for the sustainable efficient utilization of regional land resources.Methods] We used GPS positioning technology to investigate and sample the irrigation water, irrigation drainage, and soil under four typical land use types in the area of Lower Tarm River in different seasons. We combined those data with indoor measurement results to determine the variation characteristics of salinity and salt ions in the irrigation area.Results] The soil in the study area was alkaline, and the salt type was mainly sulfate-chloride. The salt content was between 2.44 and 118.05 g/kg, and the pH value was between 8.05 and 8.34. The overall changes of soil salt content and pH value under different land use types in each season followed the order of salt wasteland > saline-alkali grassland > cultivated land and forest land. Analysis of samples from different soil depths indicated surface accumulation of salinity in June and October, and no obvious pattern in March and December. There was an obvious surface accumulation of salt in salt wasteland and saline-alkali grassland in different seasons at different soil depths. Forest land had no obvious salt accumulation pattern in each season. Because of the geographical location of the reservoir, the groundwater level in the study area was shallow (1.4-3.51 m), the groundwater salinity was high (1.56-21.30 g/L), and the salt ions in irrigation water and groundwater were mainly Na⁺ and Cl^-.Conclusion] The soil salinization characteristics under different land use types in the study area were mainly affected by factors such as surface coverage, crop types, and irrigation events. The quality of groundwater and irrigation water was an important factor affecting the soil salt content and salt ion type in the study area. Certain measures should be taken to control the groundwater level and salt content so as to protect existing cultivated land and forest land. The irrigation and drainage water of high salt content from farmland should be discharged to the salt wasteland. In the future, relevant research should be conducted on the spatial configuration of agricultural land and salt wasteland, and the rational allocation of salt discharge land would be conducive to the desalination of farmland.