Study On The Relationship Between Soil Salinization Characteristics And Irrigation Water Quality In Desert Oasis

Precipitation is scarce and evaporates is instense in desert areas.Groundwater is the main water source for the development of oasis agriculture,and the ecological environment caused by its exploitation has always been a concern.However,whether water resources can be used sustainably and the containment of soil salinization,desertification,and vegetation degradation can be controlled efficiently that caused by unreasonable irrigation or not are directly related to the sustainable development of oasis agriculture.This article takes the largest desert oasis in the Inner Mongolia Alxa,Yaoba Oasis as an example.The characteristics of soil salinization and its response to groundwater chemical characteristics of oasis development have been studied in the past 50 years,on the basis of data collection,field surveys and experiments.This study will identify the formation mechanism of soil salinization,the progress of irrigation water quality on soil salinization,aiming to improve the oasis ecosystem,maintain the healthy development of agriculture,provide scientific basis for the management of oasis water resources and policy development.The result of the study also can provide reference for the development of other oasis similar research.?1?Statistical analysis of the characteristics of soil salinity and chemical composition of irrigation water.Research indicates:saline soil in the study area accouts for about 80%of total area,which is dominated by chlorinated saline soil and sulpHite soil.The main chemical types of irrigation water are SO₄·Cl-Ca·Na.The main anions in both soil and irrigation water are SO₄^2-,Cl^-and the main cations are Ca²⁺,Na⁺+K⁺.Irrigation water chemistry is highly correlated with soil salt composition,where Cl^-?Na⁺+K⁺?SO₄^2-are the main influence ions in the formation of soil salinization.?2?Identify the spatial and temporal distribution of soil salinity and chemical components of irrigation water.Research indicates:Spatial and temporal variations of soil salinity are similar to that of irrigation water quality.In time scale,the salt content in soil and irrigation water increased exponentially.In spatial scale,the distribution of surface soil salinity is island-like centered on the saline-alkali land in southwest and west,the sand-control station in the west and the south of Tu Rigen in the south;The chemical composition of irrigation water in the southwestern saline-alkaline lands,the Red Guards-Nantian team-Tangendalai seven teams showed a high content of island-like distribution.Spatially,the content is generally increasing from northeast to southwest in soil and irrigation water.Regional differences are affected by random factors such as parent material,topography,hydrogeological conditions,vegetation and human activities.?3?Summarize the vertical distribution of salt content in soil profile.Research indicates:The types of soil profiles in the study area were divided into top-soil,mid-soil and bottom-soil type through the Q-type cluster analysis method.The salt depth of the surface of the top-soil is less than 20cm,the salt depth of the mid-soil is approximately 60⁸0cm,and the salt depth of the bottom-soil is approximately 140cm.The salinity of the soil profile of the Yaoba oasis is mostly dominated by surface accumulation,and large-area soil is in the period of salt accumulation.Soil salinity is concentrated in the tillage layer.?4?Reveal the characteristics of soil salinity and irrigation water along the groundwater runoff.Research indicates:In the direction of groundwater runoff,both showed a consistent trend of change.The main impact ions were all changed from HCO₃^-,by Cl^-,and finally to SO₄^2-.Affected by irrigation,mechanical composition of sediments,and evaporation,the soil profile types are changed from bottom-soil,mid-soil and top-soil type.Irrigation water quality in 0⁴0 cm soil layer had a significant effect on soil salinity.The main response ions were Na⁺+K⁺>Cl^->SO₄^2->Ca²⁺>Mg²⁺>HCO₃^-in irrigation water.