Analysis on Properties of Topsoil Salinity along the Shelterbelts of the Tarim Desert Highway

Abstract

The shelterbelts along the Tarim Desert Highway are faced with serious topsoil salinization and the adaptability of plants irrigated with high-saline water.Based on the field observation,some samples of topsoil and groundwater were collected along the Tarim Desert Highway.According to the analyzed results of 56 soil samples and 49 groundwater samples,in this paper the properties of topsoil salinity along the shelterbelts of the Tarim Desert Highway are discussed.The content,chemical components and spatial distribution of topsoil salinity are analyzed. The results are as follows:(1) The topsoil salinity along the shelterbelts of the Tarim Desert Highway is high because of the high evaporation and severe environment in the Taklimakan Desert;(2) The correlation between electric conductivity and salinity of groundwater is very significant(R~2=0.673).The linear correlation between soil electric conductivity and topsoil salinity is determined,and the dependent equation is developed;(3) High salt accumulation occurs in topsoil,and the total salt content is as high as 257.94 g/kg.The dominant anion from salt in soil is Cl~-,accounting for 54.12%～96.95%of the total anion,and then SO_4~(2-) and HCO_3~-;the dominant cation is Na~+,its proportion is as high as 77.41%～88.53%of the total cation,then Mg~(2+) and Ca~(2+) with proportions of 4.68%～11.90%and 1.08%～8.69%respectively.The correlation coefficient between Na~+ and Cl~-is 0.97 indicating that the dominant soluble salt is NaCl,and then Na_2SO_4,MgCl_2 and CaCl_2.There are high correlations between electric conductivity and concentrations of Cl~-,Na~+ and salt content in topsoil,and their correlation coefficients are 0.862,0.813 and 0.815 respectively;(4) The spatial variability of topsoil salinity,pH value and electric conductivity of topsoil shows that the variation of salinity and electrical conductivity of topsoil is moderate, the variation of pH value is rather weak,and the pH value of topsoil along the shelterbelts of the Tarim Desert Highway increases gradually from north to south.These results are expected to provide some scientific insights on the plant growth of the shelterbelts along the Tarim Desert Highway and the management of groundwater resources, and can also shed a light of the sustainability of shelterbelts along the Tarim Desert Highway.